LED leadframe or LED substrate, semiconductor device, and method for manufacturing LED leadframe or LED substrate

ABSTRACT

An LED leadframe or LED substrate includes a main body portion having a mounting surface for mounting an LED element thereover. A reflection metal layer serving as a reflection layer for reflecting light from the LED element is disposed over the mounting surface of the main body portion. The reflection metal layer comprises an alloy of platinum and silver or an alloy of gold and silver. The reflection metal layer efficiently reflects light emitted from the LED element and suppresses corrosion due to the presence of a gas, thereby capable of maintaining reflection characteristics of light from the LED element.

This is a Continuation of application Ser. No. 13/578,563 filed Aug. 10,2012, which in turn is a U.S. National Stage of InternationalApplication Number PCT/JP2011/058042 filed Mar. 30, 2011, and whichclaims the benefit of Japanese Application No. 2010-167298 filed Jul.26, 2010, Japanese Application No. 2010-162086 filed Jul. 16, 2010, andJapanese Application No. 2010-78854 filed Mar. 30, 2010. The disclosuresof all of the prior applications are hereby incorporated by referenceherein in their entirety.

TECHNICAL FIELD

The present invention relates to an LED leadframe or LED substrate formounting an LED element, and a method for manufacturing the same. Theinvention also relates to a semiconductor device having the LEDleadframe or LED substrate, and a method for manufacturing the same.

BACKGROUND ART

Conventionally, illumination apparatuses using LED (light emittingdiode) elements as a light source are utilized for various homeappliances, office automation equipment, vehicle display lamps, generalillumination, vehicle-mounted illumination, and displays. Someillumination apparatuses include a semiconductor device having an LEDsubstrate and an LED element.

Examples of the LED element include those that emit light in a visibleregion typically represented by red, green, and blue and an ultravioletregion. Since a wavelength distribution of the light emitted from theselight emitting elements is basically narrow, it can be said that thelight can be seen as a single color in appearance. Examples of white LEDput to practical use include those synthesizing white color by using anLED element emitting light at a high energy such as an ultraviolet or ablue color and a fluorescent material converting a portion of the lightinto light of a longer wavelength, or those synthesizing a white colorby using elements of plurality of colors.

As the semiconductor device described above, Patent literature 1describes, for example, those in which a concave portion is formed onone surface of a Cu substrate, an LED element is mounted on the concaveportion, Cu interconnect layer for connection is formed over aninsulating layer disposed on the side of the concave portion, a terminalportion of the LED and the Cu interconnect layer are connected eachother by a wire bonding, and the terminal portion and the Cuinterconnected layer are resin-encapsulated. Further, in the Patentliterature 1, Ag plating is applied to the surface of the Cuinterconnect layer.

PRIOR ART LITERATURE Patent Literature

Patent literature 1: JP-A-2006-245032

DISCLOSURE OF THE INVENTION

If an LED having high luminance is used among others, a resinencapsulating a semiconductor device for an LED is exposed to intenselight. Therefore, weather proofness has been required to the resin inrecent years. There is also an increased demand for the use of asilicone resin as such a resin. However, since the gas barrier propertytends to be poor if the silicone resin is used, a corrosive gas such asoxygen or hydrogen sulfide gas in atmospheric air penetrates as far asthe Ag layer inside the semiconductor device. Since Ag is easily reactedwith the hydrogen sulfide gas or the like to form a product such assilver sulfide, this results in a problem that an Ag layer is discoloredin the appearance and the reflectance of the Ag layer is remarkablydeteriorated for the entire visible region.

The present invention has been made in view of the above, and it is anobject of the present invention to provide an LED leadframe or LEDsubstrate that efficiently reflects light from an LED element and cansuppress corrosion due to the presence of a gas thereby maintaining thereflection characteristics of light from the LED element, and a methodfor manufacturing the same, as well as a semiconductor device and amethod for manufacturing the same.

The present invention provides an LED leadframe or LED substrate formounting an LED element, including: a main body portion having amounting surface for mounting the LED element thereover; and areflection metal layer disposed on the mounting surface of the main bodyportion, the reflection metal layer serving as a reflection layer forreflecting light from the LED element. The reflection metal layercomprises an alloy of gold and silver.

The present invention provides the LED leadframe or LED substrate inwhich the reflection metal layer has a composition containing 5 to 50%by weight of gold and the balance being silver and an inevitableimpurity.

The present invention provides a semiconductor device including: an LEDleadframe or LED substrate including a main body portion, the main bodyportion having a mounting surface for mounting an LED element thereover;an LED element mounted over the mounting surface of the main bodyportion of the leadframe or substrate; an electroconductive portion forelectrically connecting the leadframe or substrate and the LED element;and an encapsulating resin portion for encapsulating the LED element andthe electroconductive portion. A reflection metal layer is disposed overthe mounting surface of the main body portion of the LED leadframe orLED substrate, the reflection metal layer serving as a reflection layerfor reflecting light from the LED element. The reflection metal layercomprises an alloy of gold and silver.

The present invention provides the semiconductor device in which thereflection metal layer has a composition containing 5 to 50% by weightof gold and the balance being silver and an inevitable impurity.

The present invention provides the semiconductor device in which theencapsulating resin portion comprises a silicone resin.

The present invention provides the semiconductor device furtherincluding an outer resin portion surrounding the LED element and havinga concave portion. The encapsulating resin portion is filled in aconcave portion of the outer resin portion.

The present invention provides a method for manufacturing an LEDleadframe or LED substrate for mounting an LED element, including: astep of preparing a main body portion having a mounting surface formounting the LED element thereover; and a step of forming a reflectionmetal layer serving as a reflection layer over the side of the mountingsurface of the main body portion. The reflection metal layer comprisesan alloy of gold and silver.

The present invention provides a method for manufacturing asemiconductor device, including a step of fabricating a leadframe orsubstrate by the method for manufacturing the LED leadframe or LEDsubstrate; a step of mounting the LED element over the mounting surfaceof the main body portion of the leadframe or substrate; a step ofconnecting the LED element and the leadframe or substrate by anelectroconductive portion; and a step of resin-encapsulating the LEDelement and the electroconductive portion by an encapsulating resin.

The present invention provides an LED leadframe or LED substrate formounting an LED element, including: a main body portion having amounting surface for mounting the LED element thereover; and areflection metal layer disposed on the mounting surface of the main bodyportion, the reflection metal layer serving as a reflection layer forreflecting light from the LED element. The reflection metal layercomprises an alloy of gold and silver. The main body portion comprisescopper or a copper alloy. An intermediate layer is disposed between thereflection metal layer and the main body portion. The intermediate layerhas a nickel layer and a gold layer disposed successively from the sideof the main body portion.

The present invention provides the LED leadframe or LED substrate inwhich the reflection metal layer has a composition containing 5 to 50%by weight of gold and the balance being silver and an inevitableimpurity.

The present invention provides the LED leadframe or LED substrate inwhich the intermediate layer further has a copper layer disposed on thenickel layer on the side of the main body portion.

The present invention provides a semiconductor device including: an LEDleadframe or LED substrate including a main body portion, the main bodyportion having a mounting surface for mounting an LED element thereover;an LED element mounted over a mounting surface of the main body portionof the leadframe or substrate; an electroconductive portion forelectrically connecting the leadframe or substrate and the LED element;and an encapsulating resin portion for encapsulating the LED element andthe electroconductive portion. A reflection metal layer is disposed overthe mounting surface of the main body portion of the LED leadframe orLED substrate, the reflection metal layer serving as a reflection layerfor reflecting light from the LED element. The reflection metal layercomprises an alloy of gold and silver. The main body portion comprisescopper and copper alloy. An intermediate layer is provided between thereflection metal layer and the main body portion. The intermediate layerhas a nickel layer and a gold layer disposed successively from the sideof the main body portion.

The present invention provides the semiconductor device in which thereflection metal layer has a composition containing 5 to 50% by weightof gold and the balance being silver and an inevitable impurity.

The present invention provides the semiconductor device in which theintermediate layer further has a copper layer disposed on the nickellayer on the side of the main body portion.

The present invention provides the semiconductor device in which theencapsulating resin portion comprises a silicone resin.

The present invention provides the semiconductor device furtherincluding an outer resin portion surrounding the LED element and havinga concave portion. The encapsulating resin portion is filled in theconcave portion of the outer resin portion.

The present invention provides a method for manufacturing the LEDleadframe or LED substrate for mounting an LED element, including: astep of preparing a main body portion having a mounting surface formounting the LED element thereover; a step of forming an intermediatelayer to the main body portion; a step of forming a reflection metallayer serving as a reflection layer on the intermediate layer. Thereflection metal layer comprises an alloy of gold and silver. The mainbody portion comprises copper or a copper alloy. The intermediate layerhas a nickel layer and a gold layer disposed successively from the sideof the main body portion.

The present invention provides a method for manufacturing asemiconductor device, including: a step of preparing a main body portionhaving a mounting surface for mounting an LED element thereover; a stepof forming an intermediate layer on the main body portion; a step offorming a reflection metal layer serving as a reflection layer on theintermediate layer; a step of mounting an LED element over the mountingsurface of the main body portion, and connecting the LED element and themain body portion by an electroconductive portion; and a step ofencapsulating the LED element and the electroconductive portion by alight permeable encapsulating resin portion. The reflection metal layercomprises an alloy of gold and silver. The main body portion comprisescopper or a copper alloy. The intermediate layer has a nickel layer anda gold layer disposed successively from the side of the main bodyportion.

The present invention provides an LED leadframe or LED substrate formounting an LED element, including: a main body portion having a die padfor mounting the LED element, and a lead portion disposed in spacedrelation to the die pad; a silver plating layer disposed on both of thedie pad and the lead portion provided on the main body portion; and anindium plating layer disposed on the silver plating layer, the indiumplating layer serving as a reflection layer for reflecting light fromthe LED element.

The present invention provides the LED leadframe or LED substrate inwhich an underlying plating layer for enhancing the bondability betweenthe main body portion and the silver plating layer is disposed betweenthe body portion and the silver plating layer.

The present invention provides a semiconductor device including: an LEDleadframe or LED substrate including a main body portion having a diepad for mounting the LED element, and a lead portion disposed in spacedrelation to the die pad; the LED element mounted over the die pad of themain body portion of the leadframe or substrate; an electroconductiveportion electrically connecting the leadframe or substrate and the LEDelement; and an encapsulating resin portion for encapsulating the LEDelement and the electroconductive portion. A silver plating layer isdisposed on both of the die pad and the lead portion provided on themain body portion of the LED leadframe or LED substrate. An indiumplating layer serving as a reflection layer for reflecting light fromthe LED element is disposed on the silver plating layer.

The present invention provides the semiconductor device in which anunderlying plating layer for enhancing the bondability between the mainbody portion and the silver plating layer is disposed between the mainbody portion and the silver plating layer.

The present invention provides the semiconductor device in which theencapsulating resin portion comprises a silicone resin.

The present invention provides the semiconductor device furtherincluding an outer resin portion surrounding the LED element and havinga concave portion. The encapsulating resin portion is filled in theconcave portion of the outer resin portion.

The present invention provides a method for manufacturing an LEDleadframe or LED substrate for mounting an LED element, including: astep of preparing a main body portion having a die pad for mounting theLED element and a lead portion disposed in spaced relation to the diepad; a step of forming a silver plating layer on both of the die pad andthe lead portion provided on the main body portion; and a step offorming an indium plating layer serving as a reflection layer on thesilver plating layer.

The present invention provides the method for manufacturing the LEDleadframe or LED substrate, further including a step of providing anunderlying plating layer for enhancing the bondability between the mainbody portion and the silver plating layer over the main body portionbefore the step of forming the silver plating layer.

The present invention provides a method for manufacturing asemiconductor device, including: a step of fabricating a leadframe orsubstrate by the method for manufacturing the LED leadframe or LEDsubstrate according to claim 25; a step of mounting the LED element overthe die pad of the main body portion of the leadframe or substrate; astep of connecting the LED element and the leadframe or substrate by anelectroconductive portion; and a step of resin-encapsulating the LEDelement and the electroconductive portion by an encapsulating resin.

The present invention provides an LED leadframe or LED substrate formounting an LED element, including: a main body portion having amounting surface for mounting the LED element thereover; and areflection plating layer disposed over the mounting surface of the mainbody portion, the reflection plating layer serving as a reflection layerfor reflecting light from the LED element. The reflection plating layercomprises an alloy of tin and silver.

The present invention provides the LED leadframe or LED substrate inwhich the reflection plating layer contains 10 to 50 wt % of tin and thebalance being silver and an inevitable impurity.

The present invention provides a semiconductor device including: an LEDleadframe or LED substrate including a main body portion, the main bodyportion having a mounting surface for mounting an LED element thereover;an LED element mounted over the mounting surface of the main bodyportion of the leadframe or substrate; an electroconductive portion forelectrically connecting the leadframe or substrate and the LED element;and an encapsulating resin portion for encapsulating the LED element andthe electroconductive portion. A reflection plating layer serving as areflection layer for reflecting light from the LED element is disposedon the mounting surface of the main body portion of the LED leadframe orLED substrate. The reflection plating layer comprises an alloy of tinand silver.

The present invention provides the semiconductor device in which thereflection plating layer contains 10 to 50 wt % of tin and the balancebeing silver and an inevitable impurity.

The present invention provides the semiconductor device in which theencapsulating resin portion comprises a silicone resin.

The present invention provides the semiconductor device furtherincluding an outer resin portion surrounding the LED element and havinga concave portion. The encapsulating resin portion is filled in theconcave portion of the outer resin portion.

The present invention provides a method for manufacturing an LEDleadframe or LED substrate for mounting the LED element, including: astep of preparing a main body portion having a mounting surface formounting the LED element thereover; and a step of forming a reflectionplating layer serving as a reflection layer to the mounting surface ofthe main body portion. The reflection plating layer comprises an alloyof tin and silver.

The present invention provides the LED leadframe or LED substrate inwhich the reflection plating layer contains 10 to 50 wt % of tin and thebalance being silver and an inevitable impurity.

The present invention provides a method for manufacturing asemiconductor device, including: a step of fabricating a leadframe orsubstrate by the method for manufacturing the LED leadframe or LEDsubstrate; a step of mounting an LED element over the mounting surfaceof the main body portion of the leadframe or substrate; a step ofconnecting the LED element and the leadframe or substrate by anelectroconductive portion; and a step of resin-encapsulating the LEDelement and the electroconductive portion by an encapsulating resin.

According to the present invention, light from the LED element can bereflected efficiently at the reflection metal layer (reflection platinglayer), as well as the reflection metal layer (reflection plating layer)does not suffer from corrosion by a corrosive gas such as oxygen andhydrogen sulfide gas in an air, and the reflection characteristicsthereof in the entire visible light region or entire ultraviolet-visiblelight region, or at least a portion of the visible light region can bemaintained high.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross sectional view showing a leadframe or substrateaccording to a first embodiment of the present invention;

FIG. 2 is a cross sectional view showing a modified example of aleadframe or substrate according to a first embodiment of the presentinvention;

FIG. 3 is a cross sectional view showing a semiconductor deviceaccording to the first embodiment of the present invention;

FIG. 4 is a diagram showing a method for manufacturing a leadframeaccording to the first embodiment of the present invention;

FIG. 5 is a diagram showing a method for manufacturing a semiconductordevice according to the first embodiment of the present invention;

FIG. 6 is a cross sectional view showing a modified example of thesemiconductor device according to the first embodiment of the presentinvention;

FIG. 7 is a cross sectional view showing a modified example of thesemiconductor device according to the first embodiment of the presentinvention;

FIG. 8 is a cross sectional view showing a modified example of thesemiconductor device according to the first embodiment of the presentinvention;

FIG. 9 is a cross sectional view showing a modified example of thesemiconductor device according to the first embodiment of the presentinvention;

FIG. 10 is a cross sectional view showing a modified example of thesemiconductor device according to the first embodiment of the presentinvention;

FIG. 11 is a cross sectional view showing a modified example of thesemiconductor device according to the first embodiment of the presentinvention;

FIG. 12 is a graph showing the change of reflectance in Example 1-A;

FIG. 13 is a graph showing the change of reflectance in ComparativeExample 1-A (Comparative Example 3-A);

FIG. 14 is a cross sectional view showing a leadframe or substrateaccording to a second embodiment of the present invention;

FIG. 15 is a cross sectional view showing a modified example of aleadframe or substrate according to the second embodiment of the presentinvention;

FIG. 16 is a phase diagram of an Ag—Sn alloy;

FIG. 17 is a cross sectional view (cross sectional view along line A-Ain FIG. 18) showing a semiconductor device according to the secondembodiment of the present invention;

FIG. 18 is a plan view showing the semiconductor device according to thesecond embodiment of the present invention;

FIG. 19 is a diagram showing a method for manufacturing a leadframeaccording to the second embodiment of the present invention;

FIG. 20 is a diagram showing a method for manufacturing a semiconductordevice according to the second embodiment of the present invention;

FIG. 21 is a cross sectional view showing a modified example of thesemiconductor device according to the second embodiment of the presentinvention;

FIG. 22 is a cross sectional view showing a modified example of thesemiconductor device according to the second embodiment of the presentinvention;

FIG. 23 is a cross sectional view showing a modified example of thesemiconductor device according to the second embodiment of the presentinvention;

FIG. 24 is a cross sectional view showing a modified example of thesemiconductor device according to the second embodiment of the presentinvention;

FIG. 25 is a cross sectional view showing a modified example of thesemiconductor device according to the second embodiment of the presentinvention;

FIG. 26 is a cross sectional view showing a modified example of thesemiconductor device according to the second embodiment of the presentinvention;

FIG. 27 is a cross sectional view showing a modified example of thesemiconductor device according to the second embodiment of the presentinvention;

FIG. 28 is a cross sectional view showing a modified example of thesemiconductor device according to the second embodiment of the presentinvention;

FIG. 29 is a diagram showing the change in each of substrates when acorrosion resistant test is carried out in the second embodiment of thepresent invention;

FIG. 30 is a cross sectional view showing a leadframe or substrateaccording to a third embodiment of the present invention;

FIG. 31 is a cross sectional view showing a modified example of theleadframe or substrate according to the third embodiment of the presentinvention;

FIG. 32 is a cross sectional view (cross sectional view along line B-Bin FIG. 33) showing the semiconductor device according to the thirdembodiment of the present invention;

FIG. 33 is a plan view showing the semiconductor device according to thethird embodiment of the present invention;

FIG. 34 is a diagram showing a method for manufacturing a leadframeaccording to the third embodiment of the present invention;

FIG. 35 is a diagram showing a method for manufacturing a semiconductordevice according to the third embodiment of the present invention;

FIG. 36 is a cross sectional view showing a modified example of thesemiconductor device according to the third embodiment of the presentinvention;

FIG. 37 is a cross sectional view showing a modified example of thesemiconductor device according to the third embodiment of the presentinvention;

FIG. 38 is a cross sectional view showing a modified example of thesemiconductor device according to the third embodiment of the presentinvention;

FIG. 39 is a cross sectional view showing a modified example of thesemiconductor device according to the third embodiment of the presentinvention;

FIG. 40 is a cross sectional view showing a modified example of thesemiconductor device according to the third embodiment of the presentinvention;

FIG. 41 is a cross sectional view showing a modified example of thesemiconductor device according to the third embodiment of the presentinvention;

FIG. 42 is a cross sectional view showing a modified example of thesemiconductor device according to the third embodiment of the presentinvention;

FIG. 43 is a cross sectional view showing a modified example of thesemiconductor device according to the third embodiment of the presentinvention;

FIG. 44 is view showing the change in each of substrates when acorrosion resistant test is carried out in the third embodiment of thepresent invention;

FIG. 45 is a graph showing the change of reflectance in Example 3-A;

FIG. 46 is a graph showing the change of reflectance in Example 3-B;

FIG. 47 is a cross sectional view showing a leadframe or substrateaccording to a fourth embodiment of the present invention;

FIG. 48 is a cross sectional view showing a modified example of aleadframe or substrate according to the fourth embodiment of the presentinvention;

FIG. 49 is a cross sectional view (cross sectional view along line C-Cin FIG. 50) showing the semiconductor device according to the fourthembodiment of the present invention;

FIG. 50 is a plan view showing the semiconductor device according to thefourth embodiment of the present invention;

FIG. 51 is a diagram showing a method for manufacturing a leadframeaccording to the fourth embodiment of the present invention;

FIG. 52 is a diagram showing a method for manufacturing a semiconductordevice according to the fourth embodiment of the present invention;

FIG. 53 is a cross sectional view showing the effect of a leadframeaccording to the fourth embodiment of the present invention;

FIG. 54 is a cross sectional view showing a modified example of thesemiconductor device according to the fourth embodiment of the presentinvention;

FIG. 55 is a cross sectional view showing a modified example of thesemiconductor device according to the fourth embodiment of the presentinvention;

FIG. 56 is a cross sectional view showing a modified example of thesemiconductor device according to the fourth embodiment of the presentinvention;

FIG. 57 is a cross sectional view showing a modified example of thesemiconductor device according to the fourth embodiment of the presentinvention;

FIG. 58 is a cross sectional view showing a modified example of thesemiconductor device according to the fourth embodiment of the presentinvention;

FIG. 59 is a cross sectional view showing a modified example of thesemiconductor device according to the fourth embodiment of the presentinvention; and

FIG. 60 is a graph comparing the change of the reflectance betweenExample 4-A and Comparative Example 4-A.

DESCRIPTION OF EMBODIMENTS First Embodiment

A first embodiment of the present invention is to be described withreference to FIG. 1 to FIG. 13.

Configuration of LED Leadframe or LED Substrate

First, the outline of an LED leadframe or LED substrate is to bedescribed with reference to FIG. 1 and FIG. 2. In FIG. 1 and FIG. 2, forthe explanation of the layer configuration of the LED leadframe or LEDsubstrate, a cross section of the LED leadframe or LED substrate isshown as a rectangular shape for the sake of convenience.

As shown in FIG. 1, an LED leadframe or LED substrate 10 according tothis embodiment (hereinafter referred to also as a leadframe 10 orsubstrate 10) is used for mounting an LED element 21 (to be describedlater). The LED leadframe or LED substrate 10 includes a main bodyportion 11 having a mounting surface 11 a for mounting the LED element21, and a reflection plating layer 12 disposed over the mounting surface11 a of the main body portion 11.

The main body portion 11 comprises a metal plate. Examples of thematerial for the metal plate forming the main body portion 11 includecopper, copper alloy, 42 alloy (Ni 41% Fe alloy), etc. The thickness ofthe main body portion 11 is preferably 0.05 mm to 0.5 mm in a case ofthe leadframe 10 and 0.005 mm to 0.03 mm in a case of the substrate 10although depending on the configuration of the semiconductor device.

The reflection metal layer 12 serves as a reflection layer forreflecting light from the LED element 21 and is situated at theuppermost surface of the LED leadframe or LED substrate 10. Thereflection metal layer 12 comprises an alloy of platinum (Pt) and silver(Ag) or an alloy of gold (Au) and silver (Ag) and has a high reflectanceto visible light and has a high corrosion resistance to oxygen and ahydrogen sulfide gas.

When the reflection metal layer 12 comprises the alloy of platinum (Pt)and silver (Ag), the alloy preferably has a composition containing 10 to40% by weight of platinum and the balance being silver and an inevitableimpurity and, more preferably, has a composition particularly containing20% by weight of platinum and the balance being silver and an inevitableimpurity.

On the other hand, when the reflection metal layer 12 comprises thealloy of gold (Au) and silver (Ag), the alloy preferably has acomposition containing 5 to 50% by weight of gold and the balance beingsilver and an inevitable impurity and, more preferably, has acomposition particularly containing 20% by weight of gold and thebalance being silver and an inevitable impurity.

The thickness of the reflection metal layer 12 is extremely thin and,specifically, it is preferably from 0.005 μm to 0.2 μm.

Further, a copper plating layer 13 and a silver plating layer 14 arestacked successively between the main body portion 11 and the reflectionmetal layer 12 from the side of the main body portion 11.

The copper plating layer 13 is used as an underlying layer for thesilver plating layer 14 and has a function of enhancing the bondabilitybetween the silver plating layer 14 and the main body portion 11. Thethickness of the copper plating layer 13 is preferably from 0.005 μm to0.1 μm.

Further, the silver plating layer 14 is used as an underlying layer forthe reflection metal layer 12 and has a function of enhancing thebondability between the copper plating layer 13 and the reflection metallayer 12. The thickness of the silver plating layer 14 is preferablylarger than that of the reflection metal layer 12 and, for example, 1 μmto 5 μm.

The silver plating layer 14 may comprise either matte silver plating orbright silver plating. As described above, since the reflection metallayer 12 is extremely thin, it can reveal the profile of the silverplating layer 14. For example, when the silver plating layer 14comprises a matte plating, the surface of the reflection metal layer 12can also be matt and, when the silver plating layer 14 comprises brightplating, the surface of the reflection metal layer 12 can also bebright.

As shown in FIG. 2(a), it is also possible that the copper plating layer13 is not provided. In this case, the LED leadframe or LED substrate 10has the main body portion 11, the silver plating layer 14 disposed onthe mounting surface 11 a of the main body portion 11 and the reflectionmetal layer 12 disposed on the silver plating layer 14.

Further, as shown in FIG. 2(b), it is also possible that the silverplating layer 14 is not disposed. In this case, the LED leadframe or LEDsubstrate 10 has a main body portion 11, a copper plating layer 13disposed on the mounting surface 11 a of a main body portion 11, and areflection metal layer 12 disposed on the copper metal layer 13.

Further, as shown in FIG. 2(c), it is also possible that the copperplating layer 13 and the silver plating layer 14 are not disposed. Inthis case, the LED leadframe or LED substrate 10 has a main body portion11, and a reflection metal layer 12 disposed directly on the mountingsurface 11 a of the main body portion 11.

Configuration of Semiconductor Device

Next, the first embodiment of the semiconductor device using the LEDleadframe or LED substrate shown in FIG. 1 is to be described withreference to FIG. 3. FIG. 3 is a cross sectional view showing asemiconductor device (SON type) according to the first embodiment of thepresent invention.

As shown in FIG. 3, a semiconductor device 20 has an LED leadframe 10,an LED element 21 mounted over the mounting surface 11 a of a main bodyportion 11 of the leadframe 10, and a bonding wire (electroconductiveportion) 22 electrically connecting the leadframe 10 and the LED element21.

Further, an outer resin portion 23 having a concave portion 23 a isdisposed so as to surround the LED element 21. The outer resin portion23 is integrated with the leadframe 10. Further, the LED element 21 andthe bonding wire 22 are encapsulated by a light permeable encapsulatingresin portion 24. The encapsulating resin portion 24 is filled in theconcave portion 23 a of the outer resin portion 23.

Each of the components to form the semiconductor device 20 is to bedescribed below.

The leadframe 10 has the main body portion 11 having the mountingsurface 11 a, the copper plating layer 13 disposed on the main bodyportion 11, the silver plating layer 14 disposed on the copper platinglayer 13, and the reflection metal layer 12 disposed on the silverplating layer 14 and serving as a reflection layer for reflecting lightfrom the LED element 21. Trenches 19 for enhancing the close bondabilitybetween the leadframe 10 and the outer resin portion 23 are formed onthe surface (upper surface) of the leadframe 10. Since the layerconfiguration of the leadframe 10 is identical with that describedalready with reference to FIG. 1, detailed description therefor is to beomitted. As the layer configuration of the leadframe 10, those shown inFIG. 2(a) to FIG. 2(c) may also be used.

In this embodiment, the main body portion 11 of the leadframe 10 has afirst portion 25 (die pad) on the side of the LED element 21 and asecond portion 26 (lead portion) spaced from the first portion 25. Theouter resin portion 23 is filled between the first portion 25 and thesecond portion 26. Therefore, the first portion 25 and the secondportion 26 are insulated electrically from each other. Further, a firstouter lead portion 27 is formed at the bottom of the first portion 25,and a second outer lead portion 28 is formed at the bottom of the secondportion 26. The first outer lead portion 27 and the second outer leadportion 28 are exposed to the outside from the outer resin portion 23respectively.

In the LED element 21, light emission wavelengths that range fromultraviolet light to infrared light can be selected by properlyselecting materials comprising single crystal of a compoundsemiconductor, for example, GaP, GaAs, GaAlAs, GaAsP, AlInGaP, or InGaNfor the light emitting layer. As the LED element 21, those usedgenerally so far can be used.

Further, the LED element 21 is fixed over the mounting surface 11 a ofthe main body portion 11 (strictly, on the reflection metal layer 12) inthe concave portion 23 a of the outer resin portion 23 by a solder or adie bonding paste. When the die bonding paste is used, a die bondingpaste comprising a light resistant epoxy resin or a silicone resin canbe selected.

The bonding wire 22 comprises a material of good electroconductivity,for example, gold which is connected at one end to a terminal portion 21a of the LED element 21 and at the other end to the surface of thesecond portion 26 of the main body portion 11 of the leadframe 10.

The outer resin portion 23 is formed on the leadframe 10, for example,by injection molding or transfer molding of a thermoplastic resin or athermosetting resin. The shape of the outer resin portion 23 can bevaried depending on the design of a die used for the injection moldingor transfer molding. For example, the entire shape of the outer resinportion 23 can be in a rectangular parallelepiped, cylindrical, conical,or like other shape. The bottom of the concaved portion 23 a can be in acircular, elliptic, or polygonal shape. The cross sectional shape of theside wall of the concave portion 23 a may be formed of a straight lineas shown in FIG. 3 or may be formed of a curved line.

The thermoplastic resins or the thermosetting resin used for the outerresin portion 23 is preferably selected particularly from thoseexcellent in heat resistance, weather resistance, and mechanicalstrength. For thermoplastic resin, polyamide, polyphthalamide,polyphenylene sulfide, liquid crystal polymer, polyether sulfone,polybutylene terephthalate, polyether imide, etc. can be used. Forthermosetting resin, silicone resin, epoxy resin, polyurethane, etc. canbe used. Further, when one of titanium dioxide, zirconium dioxide,potassium titanate, aluminum nitride, and boron nitride is added as alight reflecting agent in the resin, the reflectance of light from theLED element 21 can be increased at the bottom (between the first portion25 and the second portion 26) and the lateral side of the concaveportion 23 a to increase the entire light take-out efficiency of thesemiconductor device 20.

As the encapsulating resin portion 24, materials having a high lighttransmittance and a high refractive index at the light emissionwavelength of the semiconductor device 20 are preferably selected forimproving the light take-out efficiency. Accordingly, an epoxy resin orsilicone resin can be selected as the resin satisfying characteristicsof high heat resistance, weather resistance, and mechanical strength. Inparticular, when a high luminance LED is used as the LED element 21,since the sealing resin portion 24 is exposed to an intense light, theencapsulating resin portion 24 preferably comprises a silicone resinhaving high weather resistance.

Method for Manufacturing LED Leadframe

Then, a method for manufacturing the LED leadframe 10 used in thesemiconductor device 20 shown in FIG. 3 is to be described withreference to FIG. 4(a) to FIG. 4(g).

First, as shown in FIG. 4(a), a main body portion 11 comprising a metalsubstrate is prepared. For the main body portion 11, a metal substratecomprising copper, copper alloy, 42 alloy (Ni41% Fe alloy) or the likecan be used as described above. As the main body portion 11, thoseapplied with a cleaning process such as degreasing to both surfacesthereof are used preferably.

Then, a light sensitive resist is coated on the surface and the rearface of the main body portion 11, then dried, and exposed by way of adesired photomask. Thereafter, it was developed to form resist layers32, 33 for etching (FIG. 4(b)). For the light sensitive resist, thoseknown so far can be used.

Then, etching is applied by an etching solution to the main body portion11 using the resist layers 32, 33 for etching as an etching resistantfilm (FIG. 4(c)). The etching solution can be selected properly inaccordance with the material of the main body portion 11 to be used.When copper is used for the main body portion 11 for example, etchingcan be performed usually by spray etching from both surfaces of the mainbody portion 11 using an aqueous solution of ferric chloride.

Then, the resist layers 32, 33 for etching are peeled and removed. Asdescribed above, the main body portion 11 having the first portion 25and the second portion 26 spaced from the first portion 25 can beobtained (FIG. 4(d)). In this step, trenches 19 are formed in thesurface (upper surface) of the main body portion 11 by half etching.

Then, resist layers 30, 31 for plating having a desired pattern aredisposed on the surface and the rear face of the main body portion 11(FIG. 4(e)). Among them, in the resist layer 30 for surface plating, anopening 30 a is formed at a position corresponding to the portion offorming the reflection metal layer 12, and the mounting surface 11 a ofthe main body portion 11 is exposed from the opening portion 30 a. Onthe other hand, the resist layer 31 for rear face plating covers theentire rear face of the main body portion 11.

Then, electrolytic plating is applied to the main body portion 11 on theside of the surface covered with the resist layers 30, 31 for plating.Thus, metal (copper) is deposited on the main body portion 11 to form acopper plating layer 13 on the main body portion 11. In this step, acopper plating solution comprising copper cyanide and potassium cyanideas main ingredients can be used as the plating solution for electrolyticplating that forms the copper plating layer 13.

Successively, metal (silver) is deposited over the copper plating layer13 by electrolytic plating to form a silver plating layer 14 in the samemanner. In this step, as the plating solution for electrolytic platingforming the silver plating layer 14, a silver plating solutioncomprising silver cyanide and potassium cyanide as main ingredients canbe used.

Further, a metal is deposited on the silver plating layer 14 to form areflection metal layer 12 (FIG. 4(f)).

As described above, the reflection metal layer 12 comprises the alloy ofplatinum (Pt) and silver (Ag) or the alloy of gold (Au) and silver (Ag).When the reflection metal layer 12 comprises the alloy of platinum andsilver, the reflection metal layer 12 can be formed by sputtering, ionplating, or vapor deposition of the alloy. On the other hand, when thereflection metal layer 12 comprises the alloy of gold and silver, thereflection metal layer 12 can be formed by electrolytic plating. In thiscase, as the solution for the electrolytic plating, a silver platingsolution comprising silver cyanide, gold cyanide, and potassium cyanideas main ingredients can be used.

Then, by peeling the resist layers 30, 31 for plating, the leadframe 10shown in FIG. 3 used for the semiconductor device 20 can be obtained(FIG. 4(g)).

In FIG. 4(a) to FIG. 4(g), the main body portion 11 is fabricated into apredetermined shape by applying etching (FIGS. 4(a) to (d)), and thenthe copper plating layer 13, the silver plating layer 14, and thereflection metal layer 12 are formed over the main body portion 11(FIGS. 4(e) to (g)). However, this is not restrictive but the copperplating layer 13, the silver plating layer 14, and the reflection metallayer 12 may be formed first over the main body portion 11 andsubsequently the main body portion 11 may be fabricated into thepredetermined shape by etching.

Method for Manufacturing Semiconductor Device

Next, a method for manufacturing the semiconductor device 20 shown inFIG. 3 will be described with reference to FIGS. 5(a) to (e).

First, the leadframe 10 including the main body portion 11 having themounting surface 11 a and the reflection metal layer 12 serving as areflection layer for reflecting light from an LED element 21 is preparedby the steps described above (FIGS. 4(a) to (g)) (FIG. 5(a)).

Then, an outer resin portion 23 is formed by injection molding ortransfer molding of a thermoplastic resin or a thermosetting resin tothe leadframe 10 (FIG. 5(b)). Thus, the outer resin portion 23 and theleadframe 10 are formed integrally. Further in this step, a concaveportion 23 a is formed in the outer resin portion 23 and the reflectionmetal layer 12 is exposed to the outside at the bottom of the concaveportion 23 a by properly designing a die used for the injection moldingor transfer molding.

Then, the LED element 21 is mounted over the mounting surface 11 a ofthe main body portion 11 of the leadframe 10. In this step, the LEDelement 21 is placed and fixed over the mounting surface 11 a (on thereflection metal layer 12) of the main body portion 11 using a solder ora die bonding paste (die attaching step) (FIG. 5(c)).

Then, the terminal portion 21 a of the LED element 21 and the surface ofthe second portion 26 of the main body portion 11 are electricallyconnected to each other by a bonding wire 22 (wire bonding step) (FIG.5(d)).

Thereafter, the encapsulating resin portion 24 is filled in the concaveportion 23 a of the outer resin portion 23 and the LED element 21 andthe bonding wire 22 are encapsulated by the encapsulating resin portion24. Thus, the semiconductor device 20 shown in FIG. 3 can be obtained(FIG. 5(e)).

In this case, a plurality of LED elements 21 may be mounted previouslyover the leadframe 10 and the outer resin portion 23 between each of theLED elements 21 may be subjected to dicing respectively to prepare eachof the semiconductor devices 20 (refer to a second embodiment, a thirdembodiment or a fourth embodiment to be described later).

Function and Effect of this Embodiment

Then, the function and the effect of this embodiment are to bedescribed. In the semiconductor device 20 of this embodiment, thereflection metal layer 12 serving as a reflection layer is disposed overthe mounting surface 11 a of the main body portion 11 as describedabove. The reflection metal layer 12 comprises the alloy of platinum andsilver or the alloy of gold and silver. This can provide the followingfunction and effect.

That is, after lapse of a predetermined time from the manufacture of thesemiconductor device 20, a corrosive gas such as oxygen or a hydrogensulfide gas in the air penetrates into the semiconductor device 20, forexample, at a portion between the outer resin portion 23 and theencapsulating resin portion 24. According to this embodiment, thereflection metal layer 12 that serves as the reflection layer isdisposed over the mounting surface 11 a of the main body portion 11 andthe reflection metal layer 12 comprises the alloy of platinum and silveror the alloy of gold and silver. Thus, even when the corrosive gaspenetrates into the semiconductor device 20, the reflection layer(reflection metal layer 12) is less discolored or corroded and thereflectance thereof is not lowered. On the other hand, when thereflection layer is comprised only of the silver plating layer as acomparative embodiment, the reflection layer may possibly undergodiscoloration or corrosion when the corrosive gas penetrates into thesemiconductor device 20.

Further, according to this embodiment, since the reflection layercomprises the reflection metal layer 12 and has high reflectioncharacteristics, light from the LED element 21 can be reflectedefficiently.

Further, according to this embodiment, the reflection metal layer 12comprises an extremely thin film (0.005 μm to 0.2 μm) as describedabove. Accordingly, the reflection metal layer 12 is fractured partiallyby the energy applied during die attachment or wire bonding.Accordingly, a pull strength substantially identical with that when dieattaching or wire bonding is directly performed on the silver platingcan be obtained.

Further, according to this embodiment, since the thickness of thereflection metal layer 12 is extremely thin, the cost less increaseseven when relatively expensive platinum or gold is used. Further, sincethe reflection metal layer 12 comprises the alloy of platinum and silveror the alloy of gold and silver, the manufacturing cost can besuppressed compared with the use of only platinum or gold for thematerial as the reflection metal layer 12.

Modified Embodiment

Each of modified embodiments of the semiconductor device according tothis embodiment is to be described with reference to FIG. 6 to FIG. 11.In FIG. 6 to FIG. 11, portions identical with those of the embodimentshown in FIG. 3 carry the same reference numerals and detaileddescription therefor is to be omitted.

In each of the modified embodiments in FIG. 6 to FIG. 11, the reflectionmetal layer 12 comprises an alloy of platinum and silver or an alloy ofgold and silver in the same manner as the embodiment shown in FIG. 3.

FIG. 6 is a cross sectional view showing a modified embodiment (SONtype) of a semiconductor device according to this semiconductor device.The embodiment shown in FIG. 6 is different in that solder balls 41 a,41 b are used as the electroconductive portion and other configurationsare substantially identical with those of the embodiment shown in FIG. 3described above.

In a semiconductor device 40 shown in FIG. 6, an LED element 21 ismounted over a mounting surface 11 a of a main body portion 11 of aleadframe 10. In this case, a LED element 21 is mounted across a firstportion 25 (die pad) and a second portion 26 (lead portion) of the mainbody portion 11.

Further, the LED element 21 is connected to a reflection metal layer 12of the leadframe 10 by the solder balls (electroconductive portion) 41a, 41 b instead of the bonding wire 22 (flip-chip system). As shown inFIG. 6, of the solder balls 41 a, 41 b, one solder ball 41 a isconnected to the first portion 25 and the other solder ball 41 b isconnected to the second portion 26.

Instead of the solder balls 41 a, 41 b, an electroconductive portioncomprising gold bumps may also be used.

FIG. 7 is a cross sectional view showing a modified embodiment (LGAtype) of a semiconductor device according to this embodiment. Theembodiment shown in FIG. 7 is different from the embodiment shown inFIG. 3 in view of the configuration of the substrate 10, etc.

In a semiconductor device 50 shown in FIG. 7, a substrate 10 has a mainbody portion 11 having a mounting surface 11 a for mounting an LEDelement 21, and a reflection metal layer 12 mounted on the mountingsurface 11 a of the main body portion 11 and serving as a reflectionlayer for reflecting light from the LED element 21.

Among them, the main body portion 11 has a first portion (die pad) 51over which the LED element 21 is mounted, and a second portion (terminalportion) 52 spaced from the first portion 51. An encapsulating resinportion 24 is filled between the first portion 51 and the second portion52, and the first portion 51 and the second portion 52 are electricallyinsulated from each other. Further, a first external terminal 53 isformed on the bottom of the first portion 51, and a second externalterminal 54 is formed on the bottom of the second portion 52. The firstexternal terminal 53 and the second external terminal 54 are exposedrespectively outward from the encapsulating resin portion 24.

In FIG. 7, the main body portion 11 may comprise a single plating layeror a plurality of stacked plating layers.

In this state, the LED element 21 is mounted over the mounting surface11 a of the main body portion 11 in the first portion 51. Further, thesecond portion 52 of the semiconductor device 10 and the LED element 21are electrically connected by a bonding wire (electroconductive portion)22. That is, the bonding wire 22 is connected at one end to the terminalportion 21 a of the LED element 21, and the bonding wire 22 is connectedat the other end to the surface of the second portion 52.

On the other hand, the light permeable encapsulating resin portion 24encapsulates the upper portion of the substrate 10, the LED element 21,and the bonding wire 22.

While the outer resin portion 23 is not disposed in FIG. 7, this is notrestrictive, but the outer resin portion 23 may also be disposed so asto surround the LED element 21 in the same manner as in FIG. 3.

FIG. 8 is a cross sectional view showing a modified embodiment (PLCCtype) of a semiconductor device according to this embodiment. Theembodiment shown in FIG. 8 is different in view of the configuration ofa leadframe 10 from the embodiment shown in FIG. 3.

In a semiconductor device 60 shown in FIG. 8, a leadframe 10 includes amain body portion 11 having a mounting surface 11 a for mounting an LEDelement 21, and a reflection metal layer 12 disposed over the mountingsurface 11 a of the main body portion 11 for reflecting light from theLED element 21.

Among them, the main body portion 11 has a first portion (die pad) 61over which the LED element 21 is mounted and a second portion (terminalportion) 62 and a third portion (terminal portion) 63 spaced from thefirst portion 61. An outer resin portion 23 is filled between the firstportion 61 and the second portion 62 and between the first portion 61and the third portion 63 respectively. Thus, the first portion 61 andthe second portion 62 are electrically insulated from each other, andthe first portion 61 and the third portion 63 are electrically insulatedfrom each other.

Further, each of the second portion 62 and the third portion 63 iscurved in a substantially J-shaped cross sectional shape. Further, afirst outer lead portion 64 is formed on the end of the second portion62 and a second outer lead portion 65 is formed on the end of the thirdportion 63. The first outer lead portion 64 and the second outer leadportion 65 are exposed respectively outward from the outer resin portion23.

In this state, the LED element 21 is mounted over the mounting surface11 a of the main body portion 11 in the first portion 61. Further, theLED element 21 is electrically connected respectively to the secondportion 62 and the third portion 63 of the main body portion 11 of theleadframe 10 by way of bonding wires (electroconductive portion) 22.

FIG. 9 is a cross sectional view showing a modified embodiment(substrate type) of the semiconductor device according to thisembodiment. The embodiment shown in FIG. 9 is different from theembodiment shown in FIG. 3 for example in that a substrate 10 isdisposed over a non-electroconductive substrate 74.

In a semiconductor device 70 shown in FIG. 9, a substrate 10 includes amain body portion 11 having a mounting surface 11 a for mounting an LEDelement 21, and a reflection metal layer 12 disposed over the mountingsurface 11 a of the main body portion 11 and serving as a reflectionlayer for reflecting light from the LED element 21.

Among them, the main body portion 11 has a first portion 71 and a secondportion 72 spaced from the first portion 71. An encapsulating resinportion 24 is filled between the first portion 71 and the second portion72, and the first portion 71 and the second portion 72 are electricallyinsulated from each other. In this state, the LED element 21 is mountedoverriding the first portion 71 and the second portion 72.

Further, the LED element 21 is connected to the reflection metal layer12 of the leadframe 10 by solder balls (electroconductive portion) 73 a,73 b instead of the bonding wire 22 (flip-chip system). As shown in FIG.9, of the solder balls 73 a, 73 b, the solder ball 73 a is connected tothe first portion 71 and the solder ball 73 b is connected to the secondportion 72.

Instead of the solder balls 73 a, 73 b, an electroconductive portioncomprising gold bumps may also be used.

In FIG. 9, the substrate 10 is disposed over a non-electroconductivesubstrate 74. The non-electroconductive substrate 74 may be an organicsubstrate or an inorganic substrate. Examples of the organic substrateinclude organic substrates each comprising, for example, polyethersulfone (PES), polyethylene naphthalate (PEN), polyamide, polybutyleneterephthalate, polyethylene terephthalate, polyphenylene sulfide,polyether ether ketone, liquid crystal polymer, fluoro resin,polycarbonate, polynorbornene-based resin, polysulfone, polyallylate,polyamideimide, polyetherimide, or thermoplastic polyimide, etc., orcomposite substrates thereof. Further, examples of the inorganicsubstrate include glass substrate, silicon substrate, and ceramicsubstrate.

A plurality of through holes 75 are formed in the non-electroconductivesubstrate 74. An electroconductive material 76 is filled in each of thethrough holes 75. Then, the first portion 71 and the second portion 72of the main body portion 11 are electrically connected to the firstexternal terminal 77 and the second first external terminal 78respectively by way of the electroconductive material 76 in the throughholes 75. Examples of the electroconductive material 76 includeelectroconductive metals such as copper formed by plating in the throughhole 75, or an electroconductive paste containing electroconductiveparticles such as copper particles and silver particles.

While the outer resin portion 23 is not provided in FIG. 9, this is notrestrictive but the outer resin portion 23 may also be disposed so as tosurround the LED element 21 in the same manner as in the embodimentshown in FIG. 3.

FIG. 10 is a cross sectional view showing a modified embodiment of thesemiconductor device according to this embodiment (module type). Theembodiment shown in FIG. 10 is different in that a plurality ofsubstrates 10 are disposed over one non-electroconductive substrate 74.Other configurations are substantially identical with the embodimentshown in FIG. 9 described above.

In the semiconductor device 80 shown in FIG. 10, a plurality ofsubstrates 10 are disposed over one non-electroconductive substrate 74.Each of the substrates 10 includes a main body portion 11 having amounting surface 11 a for mounting an LED element 21, and a reflectionmetal layer 12 disposed over a mounting surface 11 a of the main bodyportion 11 and serving as a reflection layer for reflecting light fromthe LED element 21.

In addition, portions shown in FIG. 10 identical with those of theembodiment shown in FIG. 9 carry the same reference numerals anddetailed description therefor is to be omitted.

FIG. 11 is a cross sectional view showing a modified embodiment of thesemiconductor device according to this embodiment (SON type). Theembodiment shown in FIG. 11 is different in that two lead portions (asecond portion 92 and a third portion 93) are disposed at the peripheryof a first portion (die pad) 91 of a main body portion 11 and otherconfigurations are substantially identical with those of the embodimentshown in FIG. 3 described previously.

That is, in the semiconductor device 90 shown in FIG. 11, the main bodyportion 11 has the first portion (die pad) 91 for mounting an LEDelement 21, and a pair of lead portions (the second portion 92 and thethird portion 93) disposed at the periphery of the first portion (diepad) 91 and at a position where the second portion 92 and the thirdportion 93 are opposed to each other with the first portion 91 putbetween them.

In FIG. 11, the LED element 21 has a pair of terminal portions 21 a, andthe pair of terminal portions 21 a are connected to the second portion92 and the third portion 93 respectively by way of bonding wires 22.

The semiconductor devices 40, 50, 60, 70, 80, and 90 according to eachof the modified embodiments of this embodiment described above (FIG. 6to FIG. 11) can also provide substantially identical function and effectas those of the semiconductor device 20 shown in FIG. 3.

EXAMPLE

Then, specific examples of the LED leadframe or LED substrate accordingto this embodiment are to be described.

Three types of substrates (Example 1-A, Example 1-B, Comparative example1-A) shown below were manufactured.

Example 1-A

A copper plating layer 13 (0.05 μm thickness) was formed on a main bodyportion 11 comprising a copper plate, and a silver plating layer 14 (3μm thickness) was applied on the copper plating layer 13. Then, areflection metal layer 12 comprising an alloy of gold (Au) and silver(Ag) (0.1 thickness) was formed by plating on the silver plating layer14, thereby manufacturing a substrate 10 (Example 1-A). In this case,the reflection metal layer 12 has a composition comprising 50% by weightof gold and the balance being silver and an inevitable impurity.

Example 1-B

A substrate 10 (Example 1-B) was manufactured in the same manner as inExample 1-A except that the reflection metal layer 12 had a compositioncontaining 30% by weight of gold and the balance being silver and aninevitable impurity.

Comparative Example 1-A

A substrate (Comparative example 1-A) was manufactured by forming acopper plating layer (0.05 μm thickness) on a main body portioncomprising a copper plate and forming a silver plating layer on thecopper plating layer.

<Initial Reflectance>

The reflectance (initial reflectance) at the surfaces of the three typesof the substrates (Example 1-A, Example 1-B, and Comparative example1-A) was measured. For the measurement of the reflectance, spectralphotometer MPC-2200, UV-2550 manufactured by Shimadzu Corporation wasused.

<Reflectance after Solution Test>

For investigating the sulfurization resistance of the three types of thesubstrates (Example 1-A, Example 1-B, and Comparative example 1-A), asolution test was carried out for each of the substrates. Specifically,each of the substrates was dipped in a 0.25% aqueous solution ofammonium sulfide (R. T) for 5 min. Then, the reflectance was measured bythe same method as in the case of the initial reflectance describedabove (reflectance after solution test).

<Reflectance after Gas Test>

For investigating the sulfurization resistance of the three types of thesubstrates (Example 1-A, Example 1-B, and Comparative example 1-A), agas test was carried out for each of the substrates. Specifically, eachof the substrates was exposed in a gas containing 3 ppm of H₂S, at atemperature of 40° C. and at a humidity of 80% Rh for one hour. Then,the reflectance (reflectance after gas test) was measured by the samemethod as in the case of the initial reflectance described above.

The results are shown in FIG. 12 and FIG. 13. FIG. 12 and FIG. 13 aregraphs showing the initial reflectance, the reflectance after thesolution test, and the reflectance after the gas test for Example 1-A(gold 50 wt %) and Comparative example 1-A (silver) respectively.

As a result, it was found that the substrate of Example 1-A (gold 50 wt%) showed less lowering of the reflectance after the solution test andthe reflectance after the gas test from the initial reflectance for theentire ultraviolet and visible regions, and the reflection metal layer12 is less likely to be corroded due to a corrosive gas such as ahydrogen sulfide gas.

The substrate of Example 1-B (gold 30 wt %) has a high initialreflectance equivalent with that of silver (Comparative example 1-A) forthe entire visible region. Although the reflectance was lowered somewhatfrom the initial reflectance in both of the reflectance after thesolution test and the reflectance after the gas test, lowering in a longwavelength region was slight and the value of the reflectance in theblue region (for example, at a wavelength of 460 nm) was kept at a levelidentical with that of Example 1-A (gold 50 wt %).

The substrate of Comparative example 1-A (silver) showed significantlowering from the initial reflectance both in the reflectance after thesolution test and the reflectance after the gas test for the entirevisible region. In particular, also the value of the reflectance in theblue region (for example, at a wavelength of 460 nm) was lower thanthose of Example 1-A (gold 50 wt %) and Example 1-B (gold 30 wt %).Accordingly, the silver plating layer is likely to be corroded due tothe corrosive gas such as a hydrogen sulfide gas.

<Continuity of Wire Bonding (W/B)>

It was investigated whether continuous wire bonding can be applied ornot on the surfaces of the three types of the substrates (Example 1-A,Example 1-B, and Comparative example 1-A) described above. Specifically,wire bonding was performed continuously for 20 times to the substratesby using a wire bonding testing apparatus (HW27U-HF, manufactured byPanasonic Factory Solutions Co., Ltd.), and it was investigated whetherthe bonding wire was disconnected or not during the process.

<Wire Bonding (W/B) Strength>

It was investigated that the wire pull strength when wire bonding wasapplied on the surfaces of the three types of the substrates (Example1-A, Example 1-B, and Comparative example 1-A) described above.Specifically, a load which disconnects the bonding wire was measuredwhen the bonding wire was pulled by 0.2 mm/sec by using a pull tester(Bond tester 4000, manufactured by DAGE Co., Ltd.).

<Solder Wettability>

Solder wettability was investigated on the three types of the substrates(Example 1-A, Example 1-B, and Comparative example 1-A) described above.Specifically, solder wettability on the substrate was measured by ameniscograph method using a solder checker (SAT-5200, manufactured byRhesca Corporation). The conditions were set to solder temperature of240° C., dipping time of 10 sec, dipping depth of 2 mm, and speed of 2mm/sec. The meniscograph method evaluates solder wettability by dippinga test specimen (substrate) into a molten solder, and measuring the timewhen the repelling force of the solder without wetting the test specimenchanged to a force of pulling the test specimen after wetting. In thiscase, “zero cross time”, that is a time till the change of the vector ofthe wetting force of wetting the test specimen, was measured.

As a result, all of the three types of the substrates (Example 1-A,Example 1-B, and Comparative example 1-A) were satisfactory for all ofthe wire bonding (W/B) continuity, the wire bonding (W/B) strength, andthe solder wettability. The results are collectively shown in Table 1.

TABLE 1 Evaluation of sulfurization resistance Initial (wavelength at460 nm) Composition reflectance Reflectance Reflectance Solder ofcorrosion (wavelength 400 after solution after gas W/B evaluationwettability resistant plating to 460 nm) test (U-5) test (1H) ContinuityStrength Zero cross Example 1-A 33 to 68% 59% 52% ⊚ (Excellent) 8.4 g1.2 sec (gold 50 wt %) Example 1-B 78 to 88% 57% 50% ⊚ (Excellent) 7.7 g1.1 sec (gold 30 wt %) Comparative 85 to 92% 22% 36% ⊚ (Excellent) 7.0 g0.9 sec example 1-A (silver)

Second Embodiment

Then, a second embodiment of the present invention is to be describedwith reference to FIG. 14 to FIG. 29. The second embodiment shown inFIG. 14 to FIG. 29 are different in the configurations of each forlayers disposed over a mounting surface 11 a of a main body portion 11and other configurations are substantially identical with those of thefirst embodiment described above. In FIG. 14 to FIG. 29, portionsidentical with those of the first embodiment carry the same referencenumerals and detailed description therefor is to be omitted.

Configuration of LED Leadframe or LED Substrate

First, the outline of an LED leadframe or LED substrate is to bedescribed with reference to FIG. 14 to FIG. 16. In FIG. 14 and FIG. 15,for the explanation of the layer configuration of the LED leadframe orLED substrate, a cross section of the LED leadframe or LED substrate isshown as a rectangular shape for the sake of convenience.

As shown in FIG. 14, an LED leadframe or LED substrate 10A according tothis embodiment (hereinafter referred to also as a leadframe 10A orsubstrate 10A) has a main body portion 11 having a mounting surface 11 afor mounting the LED element 21, and a reflection plating layer 12Adisposed over the mounting surface 11 a of the main body portion 11.

Among them, the main body portion 11 comprises a metal plate. Examplesof the material for the metal plate forming the main body portion 11include copper, copper alloy, 42 alloy (Ni 41% Fe alloy), etc. Thethickness of the main body portion 11 is preferably 0.05 mm to 0.5 mm ina case of the leadframe 10A and 0.005 mm to 0.03 mm in a case of thesubstrate 10A although depending on the configuration of thesemiconductor device.

The reflection plating layer 12A serves as a reflection layer forreflecting light from the LED element 21 and is situated at theuppermost surface of the LED leadframe or LED substrate 10A. In thiscase, the reflection plating layer 12A comprises an alloy of tin (Sn)and silver (Ag), has high reflectance to visible light, and has highcorrosion resistance to oxygen and a hydrogen sulfide gas.

The reflection plating layer 12A preferably has a composition containing10 to 50% by weight of tin and the balance being an inevitable impurityand, more preferably, has a composition particularly containing 10 to25% by weight of tin and the balance being silver and an inevitableimpurity.

FIG. 16 shows a phase diagram of an Ag—Sn alloy (source: “Binary alloyphase diagram” edited by Seizo Nagasaki and Makoto Hirabayashi,published from AGNE Gijutsu Center Inc.”). Generally, in a bonding stepor a die attaching step upon manufacturing the semiconductor device, theLED leadframe or LED substrate 10A is sometimes heated, for example, toabout 400° C. Therefore, when the ratio of tin constituting thereflection plating layer 12A exceeds 25% by weight, since the reflectionplating layer 12A is recrystallized when the LED leadframe or LEDsubstrate 10A is heated, the performance tends to be changed. Further,when the ratio of tin is lowered to less than 10% by weight, since thetin ratio is decreased, the reflection plating layer 12A is liable tosuffer from corrosion by a corrosive gas such as oxygen or a hydrogensulfide gas in the air.

Further, since the melting point of the reflection plating layer 12A islowered (refer to FIG. 16) when the ratio for tin constituting thereflection plating layer 12A exceeds 70% by weight, the reflectionplating layer 12A may possibly be melted when the LED leadframe or LEDsubstrate 10A is heated, for example, to about 400° C. Further, when theratio of tin constituting the reflection plating layer 12A exceeds 50%by weight, the reflection characteristics or the bonding performance ofthe reflection plating layer 12A may possibly be degraded.

Depending on the method for manufacturing the semiconductor device, theLED leadframe or LED substrate 10A is not always heated to a hightemperature (for example, to about 400° C.). In such a case, there is nopossibility that the reflection plating layer 12A is recrystallized ormelted due to the effect of the heat. Accordingly, the ratio of tinconstituting the reflection plating layer 12A is not restricted to therange described above.

Further, the thickness of the reflection plating layer 12A is extremelythin and, specifically, it is preferably 0.005 μm to 0.2 μm.

On the other hand, an underlying plating layer 13A is interposed betweenthe main body portion 11 and the reflection plating 12A. Examples of themetal plating constituting the underlying plating layer 13A includecopper plating or nickel plating.

The underlying plating layer 13A is used as an underlayer for thereflection plating layer 12A, and has a function of enhancing thebondability between the reflection plating layer 12A and the main bodyportion 11. The thickness of the underlying plating layer 13A ispreferably from 0.005 μm to 0.1 μm.

As shown in FIG. 15, it is also possible that the underlying platinglayer 13A is not provided between the main body portion 11 and thereflection plating 12A. In this case, the LED leadframe or LED substrate10A has the main body portion 11, the reflection plating layer 12Adisposed directly on the mounting surface 11 a of the main body portion11.

Configuration of Semiconductor Device

Then, a second embodiment of the semiconductor device using the LEDleadframe or LED substrate shown in FIG. 14 is to be described withreference to FIG. 17 and FIG. 18. FIG. 17 and FIG. 18 are crosssectional views showing a semiconductor device (SON type) according tothe first embodiment of the present invention.

As shown in FIG. 17 and FIG. 18, a semiconductor device 20A according tothe second embodiment has an LED leadframe 10A, an LED element 21mounted over a mounting surface 11 a of a main body portion 11 of theleadframe 10A, and a bonding wire (electroconductive portion) 22electrically connecting the leadframe 10A and the LED element 21.

Further, an outer resin portion 23 having a concave portion 23 a isdisposed so as to surround the LED element 21. The outer resin portion23 is integrated with the leadframe 10A. Further, the LED element 21 andthe bonding wire 22 are encapsulated by a light permeable encapsulatingresin portion 24. The encapsulating resin portion 24 is filled in theconcave portion 23 a of the outer resin portion 23.

The leadframe 10A has the main body portion 11 having the mountingsurface 11 a, the copper plating layer 13A disposed on the main bodyportion 11, and the reflection plating layer 12A disposed on theunderlying plating layer 13A and serving as a reflection layer forreflecting light from the LED element 21. Trenches 19 for enhancing theclose bondability between the leadframe 10A and the outer resin portion23 are formed in the surface (upper surface) of the leadframe 10A. Sincethe layer configuration of the leadframe 10A is identical with thatdescribed already with reference to FIG. 14, detailed descriptiontherefor is to be omitted. As the layer configuration of the leadframe10A, that shown in FIG. 15 may also be used.

In addition, since the configuration for each of components to form thesemiconductor device 20A is identical with that of the first embodimentdescribed above, portions identical with those of the first embodimentdescribed above carry the same reference numerals and detaileddescription therefor is to be omitted.

Method for Manufacturing LED Leadframe

Then, a method for manufacturing the LED leadframe 10A used in thesemiconductor device 20A shown in FIG. 17 and FIG. 18 is to be describedwith reference to FIGS. 19(a) to (g). In the followings, description ofthe portions in common with those of the first embodiment describedabove is partially omitted.

First, in the same manner as in the first embodiment (FIGS. 4(a) to(d)), the main body portion 11 having a first portion 25 and a secondportion 26 spaced from the first portion 25 is manufactured (FIGS. 19(a)to (d)).

Then, resist layers 30, 31 for plating each having a desired pattern aredisposed on the surface and the rear face of the main body portion 11(FIG. 19(e)), and electrolytic plating is applied to the main bodyportion 11 on the side of the surface covered with the plating resistlayers 30, 31. Thus, a metal (copper) is deposited on the main bodyportion 11 to form an underlying plating layer 13A on the main bodyportion 11. When the underlying plating layer 13A comprises copperplating, a copper plating solution comprising copper cyanide andpotassium cyanide as main ingredients can be used as the platingsolution for electrolytic plating.

Successively, metal is deposited on the underlying plating layer 13A byelectrolytic plating to form a reflection plating layer 12A (FIG. 19(f)).

As described above, the reflection plating layer 12A comprises the alloyof tin (Sn) and silver (Ag). As the plating solution for electrolyticplating for forming the reflection plating layer 12A, non-cyanic platingsolution containing salts of silver and tin can be used.

Then, by peeling the resist layers 30, 31 for plating, a leadframe 10Aused for the semiconductor device 20A can be obtained (FIG. 19(g)).

In FIG. 19(a) to FIG. 19(g), the main body portion 11 is fabricated intoa predetermined shape by etching (FIGS. 19(a) to (d)) and then theunderlying plating layer 13A and the reflection plating layer 12A areformed over the main body portion 11 (FIGS. 19(e) to (g). However, thisis not restrictive but the underlying plating layer 13A and thereflection plating layer 12A may be formed first over the main bodyportion 11 and then the main body portion 11 may be fabricated into thepredetermined shape.

Method for Manufacturing Semiconductor Device

Then, a method for manufacturing the semiconductor device 20A shown inFIG. 17 and FIG. 18 is to be described with reference to FIGS. 20(a) to(g). In FIGS. 20(a) to (g), portions identical with those of the firstembodiment described above carry the same reference numerals.

First, by the step shown in FIGS. 19(a) to (g), a lead frame 10A ismanufactured (FIG. 20(a)), and a thermoplastic resin or a thermosettingresin is injection molded or transfer molded to the leadframe 10A, toform an outer resin portion 23 (FIG. 20(b)).

Then, an LED element 21 is mounted over the mounting surface 11 a of amain body portion 11 of the leadframe 10A. In this step, the LED element21 is placed and fixed over the mounting surface 11 a (on the reflectionplating layer 12A) of the main body portion 11 using a solder or a diebonding paste (die attaching step) (FIG. 20(c)).

Then, a terminal portion 21 a of the LED element 21 and the surface of asecond portion 26 of the main body portion 11 are electrically connectedto each other by a bonding wire 22 (wire bonding step) (FIG. 20(d)).

Then, an encapsulating resin portion 24 is filled in a concave portion23 a in the outer resin portion 23 and the LED element 21 and thebonding wire 22 are encapsulated by the encapsulating resin portion 24(FIG. 20(e)).

Then, the leadframe 10A is separated on every LED element 21 by dicingthe outer resin portion 23 between each of the LED elements 21 (FIG.20(f)). In this step, the leadframe 10A is mounted and fixed on a dicingtape 37 and then the outer resin portion 23 between each of the LEDelements 21 is cut in a vertical direction by a blade 38 comprising, forexample, a diamond grinding stone.

As described above, the semiconductor device 20A shown in FIG. 17 andFIG. 18 can be obtained (FIG. 20(g)).

Function and Effect of this Embodiment

Then, the function and the effect of this embodiment are to bedescribed. In the semiconductor device 20A of this embodiment, thereflection plating layer 12A serving as a reflection layer is disposedover the mounting surface 11 a of the main body portion 11 as describedabove. The reflection plating layer 12A comprises an alloy of tin andsilver. Then, as in the case of the first embodiment described above,even when a corrosive gas penetrates into the semiconductor device 20Aafter lapse of a predetermined time from the manufacture of thesemiconductor device 20A, the reflection layer (reflection plating layer12A) is less discolored or corroded, whereby the reflectance is notlowered.

Further, according to this embodiment, since the reflection platinglayer 12A comprises the alloy of tin and silver and has high reflectioncharacteristics, light from the LED element 21 can be reflectedefficiently.

Further, according to this embodiment, the reflection plating layer 12Acomprises an extremely thin film (0.005 μm to 0.2 μm) as describedabove. Accordingly, the reflection plating layer 12A is fracturedpartially by the energy applied upon die attachment or wire bonding.Accordingly, there can be obtained a pull strength substantiallyidentical with that when die attaching or wire bonding is performeddirectly on the silver plating.

Modified Embodiment

Each of modified embodiments of the semiconductor device according tothis embodiment is to be described with reference to FIG. 21 to FIG. 28.In FIG. 21 to FIG. 28, portions identical with those of the embodimentshown in FIG. 6 to FIG. 11 carry the same reference numerals anddetailed description therefor is to be omitted.

In each of the modified embodiments shown in FIG. 21 to FIG. 28, thereflection plating layer 12A comprises an alloy of tin and silver in thesame manner as in the embodiment shown in FIG. 17 and FIG. 18.

FIG. 21 is a cross sectional view showing a modified embodiment (SONtype) of a semiconductor device according to this embodiment. Thesemiconductor device 40A shown in FIG. 21 is different in theconfigurations for each of the layers disposed over the mounting surface11 a of the main body portion 11, and other configurations aresubstantially identical with the configurations of the semiconductordevice 40 shown in FIG. 6 described above.

FIG. 22 is a cross sectional view forming a modified embodiment (LGAtype) of a semiconductor device according to this embodiment. Thesemiconductor device 50A shown in FIG. 22 is different in theconfigurations for each of the layers disposed over the mounting surface11 a of the main body portion 11, and other configurations aresubstantially identical with those of the semiconductor device 50 shownin FIG. 7 described above.

FIG. 23 is a cross sectional view showing a modified embodiment (PLCCtype) of a semiconductor device according to this embodiment. Thesemiconductor device 60A shown in FIG. 23 is different in theconfigurations for each of the layers disposed over the mounting surface11 a of the main body portion 11, and other configurations aresubstantially identical with those of the semiconductor device 60 shownin FIG. 8 described above.

FIG. 24 is a cross sectional view showing a modified embodiment(substrate type) of a semiconductor device according to this embodiment.The semiconductor device 70A shown in FIG. 24 is different in theconfigurations for each of the layers disposed over the mounting surface11 a of the main body portion 11, and other configurations aresubstantially identical with those of the semiconductor device 70 shownin FIG. 9 described above.

FIG. 25 is a cross sectional view showing a modified embodiment (moduletype) of a semiconductor device according to this embodiment. Thesemiconductor device 80A shown in FIG. 25 is different in theconfigurations for each of the layers disposed over the mounting surface11 a of the main body portion 11, and other configurations aresubstantially identical with those of the semiconductor device 80 shownin FIG. 10 described above.

FIG. 26 is a cross sectional view showing a modified embodiment (SONtype) of a semiconductor device according to this embodiment. Thesemiconductor device 90A shown in FIG. 26 is different in theconfigurations for each of the layers disposed over the mounting surface11 a of the main body portion 11, and other configurations aresubstantially identical with those of the semiconductor device 90 shownin FIG. 11 described above.

FIG. 27 is a cross sectional view showing a modified embodiment(collectively molded type with lens) of a semiconductor device accordingto this embodiment. The embodiment shown in FIG. 27 is different in thatthe outer resin portion 23 is not disposed at the periphery of an LEDelement 21 and a lens 101 is disposed on an encapsulation resin portion24, and other configurations are substantially identical with those ofthe embodiment shown in FIG. 21 described above.

That is, in the semiconductor device 100A shown in FIG. 27, an outerresin portion 23 is filled between a first portion 25 and a secondportion 26 of the main body portion 11. On the other hand, differentfrom the embodiment shown in FIG. 21, the outer resin portion 23 is notdisposed above the leadframe 10A.

Further, in FIG. 27, a dome-shaped lens 101 is formed on the surface(upper surface) of an encapsulation portion 24 for controlling theirradiation direction of light from the LED element 21.

FIG. 28 is a cross sectional view showing a modified embodiment(collectively molded type) of a semiconductor device. The embodimentshown in FIG. 28 is different in that the LED element 21 and the bondingwire 22 are encapsulated only by the encapsulating resin portion 24, andother configurations are substantially identical with those of theembodiment shown in FIG. 17 and FIG. 18 described above.

That is, in the semiconductor device 110A shown in FIG. 28, an LEDelement 21 and a bonding wire 22 are collectively encapsulated only bythe encapsulating resin portion 24 without using the outer resin portion23. The encapsulating resin portion 24 is filled between the firstportion 25 and the second portion 26 of the main body portion 11.

Also in the semiconductor devices 40A, 50A, 60A, 70A, 80A, 90A, 100A,and 110A (FIG. 21 to FIG. 28) according to each of the modifiedembodiments of this preferred embodiment described above, substantiallyidentical function and effect with those of the semiconductor device 20Ashown in FIG. 17 and FIG. 18 can be obtained.

EXAMPLE

Next, specific examples of the LED leadframe or LED substrate accordingto this embodiment are to be described with reference to FIG. 29.

Three types of substrates (Example 2-1, Example 2-2, Comparative Example2-1) shown below were manufactured.

Example 2-1

Nickel plating was applied as an underlying plating layer 13A on a mainbody portion 11 comprising a rectangular copper plate. Then, areflection plating layer 12A comprising an alloy of tin (Sn) and silver(Ag) was formed on the underlying plating layer 13A to manufacture asubstrate 10A (Example 2-1). In this case, the reflection plating layer12A had a composition containing 20% by weight of tin and the balancebeing silver and an inevitable impurity.

Example 2-2

A substrate 10A (Example 2-2) was manufactured in the same manner as inExample 2-1 except that the reflection plating layer 12A had acomposition containing 35% by weight of tin and the balance being silverand an inevitable impurity.

Comparative Example 2-1

A substrate (Comparative Example 2-1) was manufactured in the samemanner as in Example 2-1 except that the reflection plating layercomprises a silver plating layer.

Then, glossiness at the surface of the three types of the substrates(Example 2-1, Example 2-2, Comparative Example 2-1) was measured. Forthe measurement of the glossiness, a microsurface photospectrometer VSR300 (manufactured by NIPPON DENSHOKU INDUSTRIES CO. LTD.) was used. As aresult, the substrate 10A of Example 2-1 showed a glossiness of 0.32 andexhibited half bright appearance (opaque white color). Further, thesubstrate 10A of Example 2-2 showed a glossiness of 1.25 to 0.47 and theglossiness was higher compared with that of the substrate 10A of Example2-1. On the other hand, the glossiness of the substrate of ComparativeExample 2-1 was 1.28. As a result, the values of the glossiness of threetypes of the substrates (Example 2-1, Example 2-2, and ComparativeExample 2-1) were sufficient for use as the reflection layer forreflecting light from the LED element.

Successively, a corrosion resistant test was carried out on the threetypes of the substrates (Example 2-1, Example 2-2, and ComparativeExample 2-1) described above. Specifically, the three types of thesubstrates were directly left in a gas mixture containing SO₂ (10 ppm)and H₂S (3 ppm) respectively. During leaving, the temperature was keptat 40° C. and the humidity was kept at 75% Rh at the periphery of thesubstrate. Then, the surface state of the substrate after 2 hours, 5hours, and 10 hours from the start of leaving was visually observed andthe superiority or the inferiority thereof was investigated incomparison (FIG. 29).

As a result, the substrate of Comparative Example 2-1 already starteddiscoloration after 2 hours and was discolored completely after 10hours. On the contrary, the substrates of Example 2-1 and Example 2-2showed no substantial discoloration even after lapse of 10 hours.

Third Embodiment

Then, a third embodiment of the present invention is to be describedwith reference to FIG. 30 to FIG. 46. The third embodiment shown in FIG.30 to FIG. 46 is different in the configurations for each of layersdisposed over the mounting surface 11 a of a main body portion 11, andother configurations are substantially identical with those of the firstembodiment and the second embodiment described above. In FIG. 30 to FIG.46, portions identical with those of the first embodiment and the secondembodiment carry the same reference numerals and detailed descriptiontherefor is to be omitted.

Configuration of LED Leadframe or LED Substrate

First, the outline of an LED leadframe or LED substrate is to bedescribed with reference to FIG. 30 and FIG. 31. In FIG. 30 and FIG. 31,for the explanation of the layer configuration of the LED leadframe orLED substrate, a cross section of the LED leadframe or LED substrate isshown as a rectangular shape for the sake of convenience.

As shown in FIG. 30, an LED leadframe or LED substrate 10B (hereinafterreferred to also as a leadframe 10B or substrate 10B) is used formounting an LED element 21 (to be described later). The LED leadframe orLED substrate 10B has a main body portion 11 having a mounting surface11 a for mounting the LED element 21, and an indium plating layer 12Bdisposed over the side of the mounting surface 11 a of the main bodyportion 11.

Among them, the main body portion 11 comprises a metal plate. Examplesof the material for the metal plate forming the main body portion 11include copper, copper alloy, 42 alloy (Ni 41% Fe alloy), etc. Thethickness of the main body portion 11 is preferably 0.05 mm to 0.5 mm ina case of a leadframe 10B and 0.005 mm to 0.03 mm in a case of asubstrate 10B although depending on the configuration of thesemiconductor device.

The indium plating layer 12B serves as a reflection layer for reflectinglight from the LED element 21, and is situated at the uppermost surfaceof the LED leadframe or LED substrate 10B. The indium plating layer 12Bcomprises an indium (In) plating layer, has a high reflectance to avisible light, and has a high corrosion resistance to oxygen and ahydrogen sulfide gas. Further, the thickness of the indium plating layer12B is extremely thin and, specifically, it is preferably 0.005 μm to0.2 μm.

On the other hand, an underlying plating layer 13B and a silver platinglayer 14 are interposed between the main body portion 11 and the indiumplating layer 12B successively from the side of the main body portion11.

Among them, the underlying plating layer 13B is used as an underlyinglayer for the silver plating layer 14, and has a function of enhancingthe bondability between the silver plating layer 14 and the main bodyportion 11. Examples of the metal plating forming the underlying platinglayer 13B include copper plating or nickel plating. The thickness of theunderlying plating layer 13B is preferably 0.005 μm to 0.1 μm.

The silver plating layer 14 is used as an underlying layer for theindium plating layer 12B, and has a function of enhancing thebondability between the underlying plating layer 13B and the indiumplating layer 12B. The thickness of the silver plating layer 14 islarger than that of the indium plating layer 12B, and is preferably 1 μmto 5 μm.

The silver plating layer 14 may comprise either matte silver plating orbright silver plating. As described above, since the indium platinglayer 12B is extremely thin, it can reveal the profile of the silverplating layer 14. For example, when the silver plating layer 14comprises matte plating, the surface of the indium plating layer 12B canalso be matt and, when the silver plating layer 14 comprises brightplating, the surface of the indium plating layer 12B can also be bright.

As shown in FIG. 31, it is also possible that an underlying platinglayer 13B is not provided. In this case, the LED leadframe or LEDsubstrate 10B has the main body portion 11, the silver plating layer 14disposed on the mounting surface 11 a of the main body portion 11 andthe indium plating layer 12B disposed on the silver plating layer 14.

Configuration of Semiconductor Device

Then, a third embodiment of the semiconductor device using the LEDleadframe or LED substrate shown in FIG. 30 is to be described withreference to FIG. 32 and FIG. 33. FIG. 32 and FIG. 33 are diagramsshowing a semiconductor device (SON type) according to the thirdembodiment of the present invention.

As shown in FIG. 32 and FIG. 33, a semiconductor device 20B according tothis embodiment has an LED leadframe 10B, an LED element 21 mounted overthe mounting surface 11 a of a main body portion 11 of a leadframe 10B,and a bonding wire (electroconductive portion) 22 electricallyconnecting the leadframe 10B and the LED element 21.

Further, an outer resin portion 23 having a concave portion 23 a isdisposed so as to surround the LED element 21. The outer resin portion23 is integrated with the leadframe 10B. Further, the LED element 21 andthe bonding wire 22 are encapsulated by a light permeable encapsulatingresin portion 24. The encapsulating resin portion 24 is filled in aconcave portion 23 a of the outer resin portion 23.

The leadframe 10B has the main body portion 11 having a mounting surface11 a, an underlying plating layer 13B disposed on the main body portion11, a silver plating layer 14 disposed on the underlying plating layer13B, and an indium plating layer 12B disposed on the silver platinglayer 14 and serving as a reflection layer for reflecting light from theLED element 21. Trenches 19 for enhancing the close bondability betweenthe leadframe 10B and the outer resin portion 23 are formed in thesurface (upper surface) of the leadframe 10B. Since the layerconfiguration of the leadframe 10B is identical with that describedalready with reference to FIG. 30, detailed description therefor is tobe omitted. As the layer configuration of the leadframe 10B, one shownin FIG. 31 may also be used.

In addition, since the configuration for each of components to form thesemiconductor device 20B is identical with those of the first embodimentand the second embodiment described above, portions identical with thoseof the first embodiment and the second embodiment described above carrythe same reference numerals and detailed description therefor is to beomitted.

Method for Manufacturing LED Leadframe

Then, a method for manufacturing the LED leadframe 10B used in thesemiconductor device 20B shown in FIG. 32 and FIG. 33 is to be describedwith reference to FIGS. 34(a) to (g). In the followings, description ofthe portions in common with those of the first embodiment and the secondembodiment described above is partially omitted.

First, in the same manner as in the first embodiment and the secondembodiment (FIGS. 4(a) to (d)) and FIGS. 19(a) to (d)), a main bodyportion 11 having a first portion 25 and a second portion 26 spaced fromthe first portion 25 is manufactured (FIGS. 34(a) to (d)).

Then, resist layers 30, 31 for plating each having a desired pattern aredisposed on the surface and the rear face of the main body portion 11(FIG. 34(e)), and electrolytic plating is applied to the main bodyportion 11 on the side of the surface covered with the resist layers 30,31 for plating. Thus, a metal is deposited on the main body portion 11to form an underlying plating layer 13B on the main body portion 11.When the underlying plating layer 13B comprises copper, a copper platingsolution comprising copper cyanide and potassium cyanide as mainingredients can be used as the plating solution for electrolytic platingfor forming the underlying plating layer 13B.

Successively, metal (silver) is deposited on the underlying platinglayer 13B by electrolytic plating to form a silver plating layer 14 inthe same manner. In this case, as the plating solution for electrolyticplating for forming the silver plating layer 14, a silver platingsolution comprising silver cyanide and potassium cyanide as mainingredients can be used.

Further, metal (indium) is deposited on the silver plating layer 14 byelectrolytic plating to form an indium plating layer 12B (FIG. 34(f)) inthe same manner. As the plating solution for electrolytic plating forforming the indium plating layer 12B, a flash plating solutioncomprising an indium salt of an organic acid as a main ingredient can beused.

Then, by peeling the resist layers 30, 31 for plating, a leadframe 10Bused for the semiconductor device 20B can be obtained (FIG. 34(g)).

In FIGS. 34(a) to (g), the main body portion 11 is fabricated into apredetermined shape by etching (FIGS. 34(a) to (d)), and then theunderlying plating layer 13B, the silver plating layer 14, and theindium plating layer 12B are formed over the main body portion 11 (FIGS.34(e) to (g)). However, this is not restrictive but the underlyingplating layer 13B, the silver plating layer 14, and the indium platinglayer 12B may be formed successively first over the main body portion 11and then the main body portion 11 may be fabricated into thepredetermined shape by etching.

Method for Manufacturing Semiconductor Device

Then, a method for manufacturing the semiconductor device 20B shown inFIG. 32 and FIG. 33 is to be described with reference to FIGS. 35(a) to(g). In FIGS. 35(a) to (g), portions identical with those of the firstembodiment and the second embodiment described above carry the samereference numerals.

First, by the steps shown in FIGS. 34(a) to (g), a lead frame 10B ismanufactured (FIG. 35(a)), and a thermoplastic resin or a thermosettingresin is injection molded or transfer molded to the leadframe 10B, toform an outer resin portion 23 (FIG. 35(b)).

Then, an LED element 21 is mounted over the mounting surface 11 a of themain body portion 11 of the leadframe 10B. In this step, the LED element21 is placed and fixed over the mounting surface 11 a (on the indiumplating layer 12B) of the main body portion 11 using a solder or a diebonding paste (die attaching step) (FIG. 35(c)).

Then, a terminal portion 21 a of the LED element 21 and the surface of asecond portion 26 of the main body portion 11 are electrically connectedto each other by a bonding wire 22 (wire bonding step) (FIG. 35(d)).

Then, an encapsulating resin portion 24 is filled in the concave portion23 a in the outer resin portion 23 and the LED element 21 and thebonding wire 22 are encapsulated by the encapsulating resin portion 24(FIG. 35(e)).

Then, the leadframe 10B is separated on every LED element 21 by dicingthe outer resin portion 23 between each of LED elements 21 (FIG. 35(f)).

As described above, the semiconductor device 20B shown in FIG. 32 andFIG. 33 can be obtained (FIG. 35(g)).

Function and Effect of this Embodiment

Next, the function and the effect according this embodiment are to bedescribed. In the semiconductor device 20B according to this embodiment,the indium plating layer 12B serving as a reflection layer is disposedover the side of the mounting surface 11 a of the main body portion 11.Thus, even when a corrosive gas penetrates into the semiconductor device20B after lapse of a predetermined time from the manufacture of thesemiconductor device 20B, the reflection layer (indium plating layer12B) is less discolored or corroded, and the reflectance is not loweredin the same manner as in the first embodiment and the second embodimentdescribed above.

Further, according to this embodiment, since the indium plating layer12B has high reflection characteristics, light from the LED element 21can be reflected at a high efficiency.

Further, according to this embodiment, the indium plating layer 12Bcomprises an extremely thin film (0.005 μm to 0.2 μm) as describedabove. Accordingly, the indium plating layer 12B is fractured partiallyby the energy applied during die attachment or wire bonding.Accordingly, there can be obtained a pull strength substantiallyidentical with that when die attaching or wire bonding is performeddirectly on the silver plating.

Modified Embodiment

Each of modified embodiments of the semiconductor device according tothis embodiment is to be described with reference to FIG. 36 to FIG. 43.In FIG. 36 to FIG. 43, portions identical with those of the embodimentsshown in FIG. 6 to FIG. 11 and FIG. 21 to FIG. 28 carry the samereference numerals and detailed description therefor is to be omitted.

In each of the modified embodiments shown in FIG. 36 to FIG. 43, asilver plating layer 14 is disposed over the side of a mounting surface11 a of a main body portion 11, and an indium plating layer 12B servingas a reflection layer for reflecting light from an LED element 21 isdisposed over the silver plating layer 14 in the same manner as in theembodiment shown in FIG. 32 and FIG. 33.

FIG. 36 is a cross sectional view showing a modified embodiment (SONtype) of a semiconductor device according to this embodiment. Asemiconductor device 40B shown in FIG. 36 is different in theconfigurations for each of the layers disposed over the mounting surface11 a of the main body portion 11, and other configurations aresubstantially identical with the configurations of the semiconductordevice 40 shown in FIG. 6 and the semiconductor device 40A shown in FIG.21 described above.

FIG. 37 is a cross sectional view showing a modified embodiment (LGAtype) of a semiconductor device according to this embodiment. Asemiconductor device 50B shown in FIG. 37 is different in theconfigurations for each of the layers disposed over the mounting surface11 a of the main body portion 11, and other configurations aresubstantially identical with the configurations of the semiconductordevice 50 shown in FIG. 7 and the semiconductor device 50A shown in FIG.22 described above.

FIG. 38 is a cross sectional view showing a modified embodiment (PLCCtype) of a semiconductor device according to this embodiment. Asemiconductor device 60B shown in FIG. 38 is different in theconfigurations for each of the layers disposed over the mounting surface11 a of the main body portion 11 and other configurations aresubstantially identical with the configurations of the semiconductordevice 60 shown in FIG. 8 and the semiconductor device 60A shown in FIG.23 described above.

FIG. 39 is a cross sectional view showing a modified embodiment(substrate type) of a semiconductor device according to this embodiment.A semiconductor device 70B shown in FIG. 39 is different in theconfigurations for each of the layers disposed over the mounting surface11 a of the main body portion 11 and other configurations aresubstantially identical with the configurations of the semiconductordevice 70 shown in FIG. 9 and the semiconductor device 70A shown in FIG.24 described above.

FIG. 40 is a cross sectional view showing a modified embodiment (moduletype) of a semiconductor device according to this embodiment. Asemiconductor device 80B shown in FIG. 40 is different in theconfigurations for each of the layers disposed over the mounting surface11 a of the main body portion 11, and other configurations aresubstantially identical with the configurations of the semiconductordevice 80 shown in FIG. 10 and the semiconductor 80A shown in FIG. 25described above.

FIG. 41 is a cross sectional view showing a modified embodiment (SONtype) of a semiconductor device according to this embodiment. Asemiconductor device 90B shown in FIG. 41 is different in theconfigurations for each of the layers disposed over the mounting surface11 a of the main body portion 11 and other configurations aresubstantially identical with the configurations of the semiconductordevice 90 shown in FIG. 11 and the semiconductor device 90A shown inFIG. 26 described above.

FIG. 42 is a cross sectional view showing a modified embodiment(collectively molded type with lens) of a semiconductor device accordingto this embodiment. A semiconductor device 100B shown in FIG. 42 isdifferent in the configurations for each of the layers disposed over themounting surface 11 a of the main body portion 11, and otherconfigurations are substantially identical with those of thesemiconductor device 100A shown in FIG. 27 described above.

FIG. 43 is a cross sectional view showing a modified embodiment(collectively molded type) of a semiconductor device according to thisembodiment. A semiconductor device 110B shown in FIG. 43 is different inthe configurations for each of the layers disposed over the mountingsurface 11 a of the main body portion 11, and other configurations aresubstantially identical with those of the semiconductor device 110Ashown in FIG. 28 described above.

Also in the semiconductor devices 40B, 50B, 60B, 70B, 80B, 90B, 1008,and 110B (FIG. 36 to FIG. 43) according to each of the modifiedembodiments of this preferred embodiment described above, substantiallyidentical function and effect with those of the semiconductor device 20Bshown in FIG. 32 and FIG. 33 can be obtained.

EXAMPLE

Then, specific examples of the LED leadframe or LED substrate accordingto this embodiment are to be described with reference to FIG. 44 to FIG.46.

Example 3-1

First, nickel plating was applied as an underlying plating layer 13B ona main body portion 11 comprising a rectangular copper plate. Then, abright silver plating layer was formed on the underlying plating layer13B by electrolytic plating. Then, an indium plating layer 12B wasformed on the silver plating layer 14 by electrolytic plating (flashplating) to manufacture a substrate 10B (Example 3-1).

Comparative Example 3-1

Nickel plating was applied as an underlying plating layer on arectangular copper plate and then a silver plating layer was formed onthe underlying plating layer to manufacture a substrate (ComparativeExample 3-1). In this case, the silver plating layer serves as areflection layer for reflecting light from the LED element.

Then, glossiness at the surface of the two substrates (Example 3-1 andComparative Example 3-1) was measured. For the measurement of theglossiness, a microsurface photospectrometer (VSR 300, manufactured byNIPPON DENSHOKU INDUSTRIES CO. LTD.) was used. As a result, theglossiness was 1.33 for the substrate 10B according to Example 3-1. Onthe other hand, the glossiness of the substrate according to ComparativeExample 3-1 was 1.28. As a result, the values of the glossiness of thetwo substrates (Example 3-1 and Comparative Example 3-1) were sufficientto be used for the reflection layer for reflecting light from the LEDelement.

Successively, a corrosion resistant test was carried out on the twotypes of the substrates (Example 3-1 and Comparative Example 3-1)described above. Specifically, the substrates were directly left in agas mixture containing SO₂ (10 ppm) and H₂S (3 ppm) respectively.Meanwhile, the temperature was kept at 40° C. and the humidity was keptat 75% Rh at the periphery of the substrate. Then, the surface state ofthe substrates after 2 hours, 5 hours, and 10 hours from the start ofleaving was visually observed and the superiority or the inferioritythereof was investigated in comparison (FIG. 44).

As a result, the substrate of Comparative Example 3-1 already starteddiscoloration after 2 hours and was discolored completely after 10hours. On the contrary, the substrates 10B of Example 3-1 showed nosubstantial discoloration even after lapse of 10 hours. In view of theabove, it was found that the indium plating layer 12B disposed on thesilver plating 14 of the substrate 10B had a high corrosion resistance.

Then, three types of substrates (Example 3-A, Example 3-B, andComparative Example 3-A) shown below were manufactured.

Example 3-A

An underlying plating layer 13B comprising nickel plating (0.1 μmthickness) was formed on a main body portion 11 comprising a copperplate, and a silver plating layer 14 (3 μm thickness) was applied on theunderlying plating layer 13B. Then, a indium plating layer 12B (about 50nm thickness) was formed on the silver plating layer 14 by electrolyticplating (flash plating) to manufacture a substrate 10B (Example 3-A).

Example 3-B

A substrate 10B was prepared in the same manner as in Example 3-A exceptthat the thickness of the indium plating layer 12B was about 10 nm(Example 3-B).

Comparative 3-A

A copper plating layer (0.1 μm thickness) was formed on a main bodyportion 11 comprising a copper plate, and a silver plating layer (3 μmthickness) was formed on the copper plating layer to manufacture asubstrate (Comparative Example 3-A). The substrate (Comparative Example3-A) is identical with the substrate according to Comparative Example1-A described above.

<Initial Reflectance>

The reflectance (initial reflectance) at the surface of the three typesof the substrates (Example 3-A, Example 3-B, and Comparative Example3-A) was measured.

<Reflectance after Solution Test>

Further, for investigating the sulfurization resistance of the threetypes of the substrates (Example 3-A, Example 3-B, and ComparativeExample 3-A), a solution test was carried out on each of the substratesand the reflectance after the solution test was measured.

<Reflectance after Gas Test>

Further, for investigating the sulfurization resistance of the threetypes of the substrates (Example 3-A, Example 3-B, and ComparativeExample 3-A), a gas test was carried out for each of the substrates andthe reflectance after the solution test was measured.

Measuring methods for the initial reflectance, the reflectance after thesolution test, and the reflectance after the gas test were identicalwith those in the case of the first embodiment described above (Example1-A, Example 1-B, and Comparative example 1-A).

The results are shown in FIG. 45, FIG. 46, and FIG. 13. FIG. 45, FIG.46, and FIG. 13 are graphs showing the initial reflectance, thereflectance after the solution test, and the reflectance after the gastest on Example 3-A, Example 3-B, and Comparative Example 3-Arespectively (Comparative Example 3-A shown in FIG. 13 was identicalwith the case of Comparative Example 1-A).

As a result, it was found that, for the substrate of Example 3-A (In atabout 50 nm), the initial reflectance is high and satisfactory for thereflectance in a ultraviolet region compared with Comparative Example1-A (silver), that both of the reflectance after the solution test andthe reflectance after the gas test were changed scarcely from theinitial reflectance over the entire ultraviolet and visible regions, andthat the indium plating layer 12B had less possibility of undergoingcorrosion by a corrosive gas such as a hydrogen sulfide gas.

In the substrate of Example 3-B (In at about 10 nm), the initialreflectance was equivalent to that of Comparative Example 1-A (silver),and was satisfactory in the entire visible region. In addition, thereflectance after the gas test showed less lowering from the initialreflectance in the entire ultraviolet and visible regions. On the otherhand, for the reflectance after the solution test, the reflectancelowered only slightly in a long wavelength region. In addition, althoughit showed some lowering from the initial reflectance in the blue region,values were also with no problem.

The substrate of Comparative Example 3-A (silver) (Comparative Example1-A (silver)) showed significant lowering from the initial reflectanceboth in the reflectance after the solution test and the reflectanceafter the gas test and it can be said that the silver plating layer maypossibly suffer from corrosion by a corrosive gas such as a hydrogensulfide gas.

<Continuity of Wire Bonding (W/B)>

It was investigated whether wire bonding can be performed continuouslyor not on the surface of the three types of the substrates (Example 3-A,Example 3-B, and Comparative Example 3-A) described above.

<Wire Bonding (W/B) Strength>

Wire pull strength was investigated when wire bonding was performed onthe surface of the three types of the substrates (Example 3-A, Example3-B, and Comparative Example 3-A) described above.

<Solder Wettability>

Solder wettability of the three types of the substrates (Example 3-A,Example 3-B, and Comparative Example 3-A) was investigated.

Measuring methods for the continuity of wire bonding (W/B), the strengthof wire bonding (W/B), and the solder wettability are identical withthose in the case of the first embodiment described above (Example 1-A,Example 1-B, and Comparative Example 1-A).

As a result, the substrates according to Example 3-B and ComparativeExample 3-A among the three type of the substrates (Example 3-A, Example3-B, and Comparative Example 3-A) were satisfactory in all of thecontinuity of wire bonding (W/B), the wire bonding (W/B) strength, andthe solder wettability. While the continuity of the wire bonding (W/B),the wire bonding (W/B) strength, and the solder wettability were loweredin the substrate according to Example 3-A compared with the substrateaccording to Example 3-B, they were at the levels with no problemdepending on the portion to be used. The results are collectively shownin Table 2.

TABLE 2 Evaluation for sulfurization resistance Initial (wavelength 460nm) Composition reflectance Reflectance Reflectance Solder of corrosion(wavelength 400 after solution after gas W/B evaluation wettabilityresistant plating to 460 nm) test (U-5) test (1H) Continuity StrengthZero cross Example 3-A 65 to 70% 70% 72% Δ (Fair) 3.2 g 4.9 sec (In:about 50 nm) Example 3-B 82 to 88% 57% 81% ⊚ (Excellent) 6.7 g 1.0 sec(In: about 10 nm) Comparative 85 to 92% 22% 36% ⊚ (Excellent) 7.0 g 0.9sec Example 3-A (silver)

Fourth Embodiment

Then, a fourth embodiment of the present invention is to be describedwith reference to FIG. 47 to FIG. 60.

Configuration of LED Leadframe or LED Substrate

First, the outline of an LED leadframe or LED substrate is to bedescribed with reference to FIG. 47 and FIG. 48. In FIG. 47 and FIG. 48,for the explanation of the layer configuration of the LED leadframe orLED substrate, a cross section of the LED leadframe or LED substrate isshown as a rectangular shape for the sake of convenience.

As shown in FIG. 47, an LED leadframe or LED substrate 10C (hereinafteralso referred to as a leadframe 10C or a substrate 10C) is used formounting an LED element (to be described later). The LED leadframe orLED substrate 10C has a main body portion 11 having a mounting surface11 a for mounting the LED element 21, and a reflection metal layer 12Cdisposed over the main body portion 11 on the side of the mountingsurface 11 a.

Among them, the main body portion 11 comprises a metal plate. Examplesof the material for the metal plate forming the main body portion 11include copper, copper alloy, 42 alloy (Ni 41% Fe alloy), etc. Thethickness of the main body portion 11 is preferably 0.05 mm to 0.5 mm ina case of a leadframe 10C and 0.005 mm to 0.03 mm in a case of asubstrate 10C although depending on the configuration of thesemiconductor device.

The reflection metal layer 12C serves as a reflection layer forreflecting light from the LED element 21 and is situated at theuppermost surface of the LED leadframe or LED substrate 10C. Thereflection metal layer 12C comprises an alloy of platinum (Pt) andsilver (Ag) or an alloy of gold (Au) and silver (Ag), has a highreflectance to a visible light, and has a high corrosion resistance tooxygen and a hydrogen sulfide gas.

When the reflection metal layer 12C comprises the alloy of platinum (Pt)and silver (Ag), the alloy preferably has a composition containing 10 to40% by weight of platinum and the balance being silver (Ag) and aninevitable impurity and, more preferably, has a composition particularlycontaining 20% by weight of platinum and the balance being silver and aninevitable impurity.

On the other hand, when the reflection metal layer 12C comprises thealloy of gold (Au) and silver (Ag), the alloy preferably has acomposition containing 5 to 50% by weight of gold and the balance beingsilver and an inevitable impurity and, more preferably, has acomposition particularly containing 20% by weight of gold and thebalance being silver and an inevitable impurity.

The thickness of the reflection metal layer 12C is extremely thin and,specifically, it is preferably from 0.005 vim to 0.2 μm.

Further, an intermediate layer 15 is disposed between the main bodyportion 11 and the reflection metal layer 12C. The intermediate layer 15has a copper layer 16 (Cu), a nickel layer 17 (Ni), and a gold layer 18(Au) disposed successively from the side of the main body portion 11.

Among them, the copper layer 16 is used as an underlying layer for thenickel 17 and has a function of enhancing the bondability between thenickel layer 17 and the main body portion 11. The copper layer 16 can beformed, for example, by electrolytic plating. The thickness of thecopper layer 16 is preferably 0.005 μm to 0.8 μm.

Further, the nickel layer 17 is formed on the copper layer 16 by using,for example, an electrolytic plating method, and has a thickness, forexample, of 0.5 μm to 1 μm.

Further, the gold layer 18 is formed on the nickel layer 17 by using,for example, an electrolytic plating method, comprises an extremely thinlayer, and has a thickness, for example, of 0.002 μm to 1 μm.

Further, as shown in FIG. 48, it is also possible that the copper layer16 is not provided. In this case, the intermediate layer 15 has a nickellayer 17 disposed on the main body portion 11 and a gold layer 18disposed on the nickel layer 17.

Configuration of Semiconductor Device

Then, a fourth embodiment of the semiconductor device using the LEDleadframe or LED substrate shown in FIG. 49 and FIG. 50 is to bedescribed. FIG. 49 is a sectional view showing a semiconductor device(SON type) according to the fourth embodiment of the present invention,and FIG. 50 is a plan view showing a semiconductor device according tothe fourth embodiment of the present invention.

As shown in FIG. 49 and FIG. 50, a semiconductor device 20C has an LEDleadframe 10C, an LED element 21 mounted over the mounting surface 11 aof a main body portion 11 of a leadframe 10C, and a bonding wire(electroconductive portion) 22 electrically connecting the leadframe 10Cand the LED element 21.

Further, an outer resin portion 23 having a concave portion 23 a isdisposed so as to surround the LED element 21. The outer resin portion23 is integrated with the leadframe 10C. Further, the LED element 21 andthe bonding wire 22 are encapsulated by a light permeable encapsulatingresin portion 24. The encapsulating resin portion 24 is filled in aconcave portion 23 a of the outer resin portion 23.

The leadframe 10 has a main body portion 11 having a mounting surface 11a, an intermediate layer 15 disposed on the main body portion 11, and areflection metal layer 12C disposed on the intermediate layer 15 andserving as a reflection layer for reflecting light from the LED element21. The intermediate layer 15 includes the copper layer 16, the nickellayer 17, and the gold layer 18 in order from the side of the main bodyportion 11. Trenches 19 for enhancing the close bondability between theleadframe 10C and the outer resin portion 23 are formed in the surface(upper surface) of the leadframe 10C. Since the layer configuration ofthe leadframe 10C is identical with the configuration described alreadywith reference to FIG. 47, detailed description therefor is to beomitted. As the layer configuration of the leadframe 10C, that shown inFIG. 48 may also be used.

In addition, since the configurations for each of components to form thesemiconductor device 20C are identical with those of the firstembodiment to the third embodiment described above, portions identicalwith those of the first embodiment to the third embodiment describedabove carry the same reference numerals and a detailed descriptiontherefor is to be omitted.

Method for Manufacturing LED Leadframe

Then, a method for manufacturing the LED leadframe 10C used in thesemiconductor device 20C shown in FIG. 49 and FIG. 50 is to be describedwith reference to FIGS. 51(a) to (g). In the followings, description forthe portions in common with those of the first embodiment to the thirdembodiment described above is partially omitted.

First, in the same manner as in the first embodiment to the thirdembodiment (FIGS. 4(a) to (d), FIGS. 19(a) to (d) and FIGS. 34(a) to(d)), a main body portion 11 having a first portion 25 and a secondportion 26 spaced from the first portion 25 is prepared (FIGS. 51(a) to(d)).

Then, resist layers 30, 31 for plating each having a desired pattern aredisposed on the surface and the rear face of the main body portion 11(FIG. 51(e)). Among them, the resist layer 30 for plating on the side ofthe surface is formed with an opening portion 30 a at a positioncorresponding to a portion for forming the reflection metal layer 12C,and the mounting surface 11 a of the main body portion 11 is exposedthrough the opening portion 30 a. On the other hand, the resist layer 31for plating on the rear face covers the entire rear face of the mainbody portion 11.

Then, an intermediate layer 15 and a reflection metal layer 12C areformed on the surface side of the main body portion 11 (FIG. 51(f)).

In this step, electrolytic plating is first applied on the surface sideof the main body portion 11 covered with the resist layers 30, 31 forplating. Thus, a metal (copper) is deposited on the main body portion 11to form a copper layer 16 on the main body portion 11. As the platingsolution for electrolytic plating forming the copper layer 16, a copperplating solution comprising copper cyanide and potassium cyanide as mainingredients can be used.

Successively, a metal (nickel) is deposited on the copper layer 16 byelectrolytic plating to form a nickel layer in the same manner. As theplating solution for electrolytic plating for forming the nickel layer17, a plating solution of nickel sulfamate at a high nickelconcentration can be used.

Then, a metal (gold) is deposited on the nickel layer 17 by electrolyticplating to form a gold layer 18. As a plating solution for electrolyticplating for forming the gold layer 18, a gold plating solutioncomprising gold cyanide and potassium cyanide as main ingredients can beused.

The intermediate layer 15 is formed of the copper layer 16, the nickellayer 17, and the cold layer 18.

Further, a metal is deposited on the gold layer 18 of the intermediatelayer 15 to form a reflection metal layer 12C (FIG. 51(f)).

As described above, the reflection metal layer 12C comprises the alloyof platinum (Pt) and silver (Ag) or the alloy of gold (Au) and silver(Ag). When the reflection metal layer 12C comprises the alloy ofplatinum and silver, the reflection metal layer 12C can be formed bysputtering, ion plating, or vapor deposition of the alloy.

On the other hand, when the reflection metal layer 12C comprises thealloy of gold and silver, the reflection metal layer 12C can be formedby electrolytic plating in addition to sputtering, ion plating, andvapor deposition of the alloy. In this case, as the plating solution forelectrolytic plating, a silver plating solution comprising silvercyanide, gold cyanide, and potassium cyanide as main ingredients can beused.

Then, by peeling the resist layers 30, 31 for plating, the leadframe 10Cused for the semiconductor device 20C shown in FIG. 49 and FIG. 50 canbe obtained (FIG. 51(g)).

In FIGS. 51(a) to (g), after the main body portion 11 is fabricated intoa predetermined shape by etching (FIGS. 51(a) to (d)), the copper layer16, the nickel layer 17, the gold layer 18, and the reflection metallayer 12C are formed over the main body portion 11 (FIGS. 51(a) to (g)).However, this is not restrictive but the copper layer 16, the nickellayer 17, the gold layer 18, and the reflection plating layer 12C may beformed first over the main body portion 11 and then the main bodyportion 11 may be fabricated into the predetermined shape.

Alternatively, after the main body portion 11 is fabricated into apredetermined shape by etching in the steps of FIGS. 51(a) to (d), eachof the layers of the copper layer 16, the nickel layer 17, the goldlayer 18, and the reflection metal layer 12C may be formed successivelyover the entire surface of the main body portion by plating instead ofthe partial plating step in FIGS. 51(e) to (g).

Method for Manufacturing Semiconductor Device

Then, a method for manufacturing the semiconductor device 20C shown inFIG. 49 and FIG. 50 is to be described with reference to FIGS. 52(a) to(g). In FIGS. 52(a) to (g), portions identical with those of the firstembodiment to the third embodiment described above carry the samereference numerals.

First, by the step shown in FIGS. 51(a) to (g), the leadframe 10C ismanufactured (FIG. 52(a)), and a thermoplastic resin or a thermosettingresin is injection molded or transfer molded to the leadframe 10C, toform the outer resin portion 23 (FIG. 52(b)).

Then, the LED element 21 is mounted over the mounting surface 11 a ofthe main body portion 11 of the leadframe 10C. In this step, the LEDelement 21 is placed and fixed over the mounting surface 11 a (on thereflection metal layer 12C) of the main body portion 11 by using asolder or a die bonding paste (die attaching step) (FIG. 35(c)).

Then, a terminal portion 21 a of the LED element 21 and the surface of asecond portion 26 of the main body portion 11 are electrically connectedto each other by a bonding wire 22 (wire bonding step) (FIG. 52(d)).

Then, an encapsulating resin portion 24 is filled in a concave portion23 a of an outer resin portion 23 and the LED element 21 and the bondingwire 22 are encapsulated by the encapsulating resin portion 24 (FIG.35(e)).

Then, the leadframe 10C is separated on every LED element 21 by dicingthe outer resin portion 23 between each of the LED elements 21 (FIG.52(f)).

As described above, the semiconductor device 20C shown in FIG. 49 andFIG. 50 can be obtained (FIG. 52(g)).

Function and Effect of this Embodiment

Then, the function and the effect according this embodiment are to bedescribed. In the semiconductor device 20C according to this embodiment,the intermediate layer 15 is disposed between the reflection metal layer12C and the main body portion 11, and the intermediate layer 15 has thecopper layer 16, the nickel layer 17, and the gold layer 18 disposedsuccessively from the side of the main body portion 11. Thus, thefollowing function and effect can be obtained.

When the semiconductor device 20C is manufactured, heat is sometimesapplied to the leadframe 10C, for example, during die bonding (FIG.52(c)) or wire bonding (FIG. 52(d)). Specifically, during die bonding, aheat at about 300° C. to 400° C. is sometimes applied, for example, in acase of solder bonding, and a heat at about 150° C. to 200° C. issometimes applied, for example, in a case of paste connection. Further,heat at about 150° C. to 250° C. is sometimes applied, for example,during wire bonding.

In this case, as shown in FIG. 53, copper (Cu) from the main bodyportion 11 or the copper layer 16 forms an alloy with nickel in theupper layer. In this embodiment, copper (Cu) from the main body portion11 or the copper layer 16 forms an alloy with nickel and is stabilizedwith concentration gradient. As a result, diffusion thereof is stoppedby the nickel layer 17 and does not proceed above the gold layer 18.

If the main body portion comprises a copper alloy and the copper layer16 is not disposed, diffusion of the components other than copper of thecopper alloy is sometimes hindered to cause Kirkendall voids uponformation of the nickel alloy. However, the voids can be prevented bythe provision of the copper layer 16.

Accordingly, diffusion of copper (Cu) from the main body portion 11 orthe copper layer 16 to the surface of the reflection metal layer 12C isprevented. This can prevent degradation of the solder wettability or thebondability at the surface of the reflection metal layer 12C due todiffusion of copper (Cu).

Further, nickel (Ni) from the nickel layer 17 is diffused (piles up)toward Au thereabove. Pile up means that a slight amount of Ni atomsmove between dislocations of Au crystallinity due to inter-crystalmovement by thermal vibrations of Au (recrystallization) so that Niemerges at extremely local site on the surface of Au. Since thediffusion is stopped at the boundary between the gold layer 18 and thereflection metal layer 12C and does not proceed to the reflection metallayer 12C, degradation of the solder wettability and the bondability onthe surface of the reflection metal layer 12C due to diffusion of nickel(Ni) can be prevented.

Further, although silver and silver alloy allow oxygen in the air topermeate therethrough, which oxidizes the underlying metal and degradesthe bondability, gold does not allow oxygen to permeate therethrough.Accordingly, oxygen (O₂) from the air is blocked at the gold layer 18and does not proceed to the main body portion 11 and the nickel layer17. Therefore, penetration of oxygen (O₂) from the surface of thereflection metal layer 12C to the main body portion 11 can be prevented.This can prevent oxidation of the nickel layer 17 due to oxygen (O₂)from the air which may lower the pull strength between the nickel layer17 and the reflection metal layer 12C thereby causing peeling of thereflection metal layer 12C from the nickel layer 17.

As described above, according to this embodiment, diffusion of copper(Cu) contained in the main body portion 11 or the copper layer 16 to thesurface of the reflection metal layer 12C can be prevented, andpenetration of oxygen (O₂) from the surface of the reflection metallayer 12C to the main body portion 11 can be prevented. This can enhancethe heat resistance of the semiconductor device 20C, as well as reducethe thickness of the intermediate layer 15 between the reflection metallayer 12C and the main body portion 11.

Meanwhile, in the semiconductor device 20C according to this embodiment,the reflection metal layer 12C serving as the reflection layer isdisposed over the mounting surface 11 a of the main body portion 11 asdescribed above. The reflection metal layer 12C comprises the alloy ofplatinum and silver or the alloy of gold and silver. In view of theabove, even when a corrosive gas penetrates into the semiconductordevice 20C after lapse of a predetermined time from the manufacture ofthe semiconductor device 20C, the reflection layer (reflection metallayer 12C) is less discolored or corroded and the reflectance thereof isnot lowered in the same manner as in the case of the first embodiment tothe third embodiment described above.

Further, according to this embodiment, since the reflection layercomprises a reflection metal layer 12C and has high reflectioncharacteristics, it can efficiently reflect light from the LED element21.

Further, according to this embodiment, since the reflection metal layer12C is extremely thin, the increase in cost is less even when arelatively expensive platinum or gold is used. Further, since thereflection metal layer 12C comprises the alloy of platinum and silver orthe alloy of gold and silver, the manufacturing cost can be suppressedcompared with the use of only platinum or gold as the material for thereflection metal layer 12C.

Further, according to this embodiment, since the thickness of theintermediate layer 15 can be reduced (for example, about 1 μm to 2 μm),the manufacturing cost can be decreased compared with that when arelatively thick silver layer (Ag) layer is used.

Further, according to this embodiment, by applying partial metalprocessing as shown in FIG. 51(g), manufacturing cost can be decreasedcompared with that when metal processing is applied over the entiresurface.

Further, according to this embodiment, since the reflection metal layer12C and the intermediate layer 15 are thin and, accordingly, thevariation of thickness can be decreased naturally, scars formed bypressing a die to the metal surface can be decreased upon molding of theouter resin portion 23. Thus, burrs caused by resin leakage into the gapbetween the die and the metal surface can be decreased.

Further, according to this embodiment, since the reflection metal layer12C and the intermediate layer 15 are thin, the thickness of thesemiconductor device 20C can be reduced.

Each of modified embodiments of the semiconductor device according tothis embodiment is to be described with reference to FIG. 54 to FIG. 59.In FIG. 54 to FIG. 59, portions identical with those of the embodimentsshown in FIG. 6 to FIG. 11, FIG. 21 to FIG. 28, and FIG. 36 to FIG. 43carry the same reference numerals, and detailed description therefor isto be omitted.

In each of the modified examples shown in FIG. 54 to FIG. 59, anintermediate layer 15 is disposed on the side of the mounting surface 11a of a main body portion 11, and a reflection metal layer 12C serving asa reflection layer for reflecting light from an LED element 21 isdisposed on the intermediate layer 15 in the same manner as in theembodiment shown in FIG. 49 and FIG. 50.

FIG. 54 is a cross sectional view showing a modified embodiment (SONtype) of a semiconductor device according to this embodiment. Asemiconductor device 40C shown in FIG. 54 is different in theconfigurations for each of the layers disposed over the mounting surface11 a of the main body portion 11, and other configurations aresubstantially identical with the configurations of the semiconductordevice 40 shown in FIG. 6, the semiconductor device 40A shown in FIG. 21and the semiconductor device 40B shown in FIG. 36 described above.

FIG. 55 is a cross sectional view showing a modified embodiment (LGAtype) of a semiconductor device according to this embodiment. Asemiconductor device 50C shown in FIG. 55 is different in theconfigurations for each of the layers disposed over the mounting surface11 a of the main body portion 11, and other configurations aresubstantially identical with the configurations of the semiconductordevice 50 shown in FIG. 7, the semiconductor device 50A shown in FIG.22, and the semiconductor device 50B shown in FIG. 56B described above.

FIG. 56 is a cross sectional view showing a modified embodiment (PLCCtype) of a semiconductor device according to this embodiment. Asemiconductor device 60C shown in FIG. 56 is different in theconfigurations for each of the layers disposed over the mounting surface11 a of the main body portion 11, and other configurations aresubstantially identical with the configurations of the semiconductordevice 60 shown in FIG. 8, the semiconductor device 60A shown in FIG. 23and the semiconductor device 60B shown in FIG. 38 described above.

FIG. 57 is a cross sectional view showing a modified embodiment(substrate type) of a semiconductor device according to this embodiment.A semiconductor device 70C shown in FIG. 57 is different in theconfigurations for each of the layers disposed over the mounting surface11 a of the main body portion 11, and other configurations aresubstantially identical with the configurations of the semiconductordevice 70 shown in FIG. 9, the semiconductor device 70A shown in FIG.24, and the semiconductor device 70B shown in FIG. 39 described above.

FIG. 58 is a cross sectional view showing a modified embodiment (moduletype) of a semiconductor device according to this embodiment. Asemiconductor device 80C shown in FIG. 58 is different in theconfigurations for each of the layers disposed over the mounting surface11 a of the main body portion 11, and other configurations aresubstantially identical with the configurations of the semiconductordevice 80 shown in FIG. 10, the semiconductor device 80A shown in FIG.25, and the semiconductor device 80B shown in FIG. 40 described above.

FIG. 59 is a cross sectional view showing a modified embodiment (SONtype) of a semiconductor device according to this embodiment. Asemiconductor device 90C shown in FIG. 59 is different in theconfigurations for each of the layers disposed over the mounting surface11 a of the main body portion 11 and other configurations aresubstantially identical with the configurations of the semiconductordevice 90 shown in FIG. 11, the semiconductor device 90A shown in FIG.26, and the semiconductor device 90B shown in FIG. 41 described above.

Also in the semiconductor devices 40C, 50C, 60C, 70C, 80C, and 90C (FIG.54 to FIG. 59) according to each of the modified embodiments of thispreferred embodiment described above, substantially identical functionand effect with those of the semiconductor device 20C shown in FIG. 49and FIG. 50 can be obtained.

EXAMPLE

Then, specific examples of the LED leadframe or LED substrate accordingto this embodiment are to be described.

Example 4-1

A substrate 10C comprising the configuration shown in FIG. 47 (Example4-1) was manufactured. In the substrate 10C, the copper layer 16 (Cu),the nickel layer 17 (Ni), the gold layer 18 (Au), and the reflectionmetal layer 12C (alloy of gold (Au) and silver (Ag)) are stackedsuccessively over the main body portion 11 (copper substrate). The layerconfiguration is hereinafter indicated as “main body portion (coppersubstrate)/copper layer (Cu)/nickel layer (Ni)/gold layer(Au)/reflection metal layer (alloy)”.

Example 4-2

A substrate 10C comprising the configuration shown in FIG. 48 (Example4-2) was manufactured. The substrate 10C (Example 4-2) comprises a layerconfiguration of: main body portion (copper substrate)/nickel layer(Ni)/gold layer (Au)/reflection metal layer (alloy).

Comparative Example 4-1

A substrate was manufactured in which the reflection metal layer 12C wasstacked directly on the main body portion 11 without disposing theintermediate layer 15 (Comparative Example 4-1). The substrate(Comparative Example 4-1) has a layer configuration of: main bodyportion (copper substrate)/reflection metal layer (alloy).

Comparative Example 4-2

A substrate was manufactured in which only the copper layer 16 wasinterposed between the main body portion 11 and the reflection metallayer 12C (Comparative Example 4-2). The substrate (Comparative Example4-2) comprises a layer configuration of: main body portion (coppersubstrate)/copper layer (Cu)/reflection metal layer (alloy).

Comparative Example 4-3

A substrate was manufactured in which only the silver layer (Ag) wasinterposed between the main body portion 11 and the reflection metallayer 12C (Comparative Example 4-3). The substrate (Comparative Example4-3) comprises a layer configuration of: main body portion (coppersubstrate)/silver layer (Ag)/reflection metal layer (alloy).

Comparative Example 4-4

A substrate was manufactured in which the copper layer 16 and the silverlayer (Ag) were interposed between the main body portion 11 and thereflection metal layer 12C (Comparative Example 4-4). The substrate(Comparative Example 4-4) comprises a layer configuration of: main bodyportion (copper substrate)/copper layer (Cu)/silver layer(Ag)/reflection metal layer (alloy).

Comparative Example 4-5

A substrate was manufactured in which only the nickel layer 17 wasinterposed between the main body portion 11 and the reflection metallayer 12C (Comparative Example 4-5). The substrate (Comparative Example4-5) comprises a layer configuration of: main body portion (coppersubstrate)/nickel layer (Ni)/reflection metal layer (alloy).

Comparative Example 4-6

A substrate was manufactured in which the copper layer 16 and the nickellayer 17 were interposed between the main body portion 11 and thereflection metal layer 12C (Comparative Example 4-6). The substrate(Comparative Example 4-6) comprises a layer configuration of: main bodyportion (copper substrate)/copper layer (Cu)/nickel layer(Ni)/reflection metal layer (alloy).

Comparative Example 4-7

A substrate was manufactured in which the nickel layer 17 and the copperlayer were interposed between the main body portion 11 and thereflection metal layer 12C (Comparative Example 4-7). The substrate(Comparative Example 4-7) comprises a layer configuration of: main bodyportion (copper substrate)/nickel layer (Ni)/copper layer(Cu)/reflection metal layer (alloy).

Comparative Example 4-8

A substrate was manufactured in which the copper layer 16, the nickellayer 17, and the copper layer were interposed between the main bodyportion 11 and the reflection metal layer 12C (Comparative Example 4-8).The substrate (Comparative Example 4-8) comprises a layer configurationof: main body portion (copper substrate)/copper layer (Cu)/nickel layer(Ni)/copper layer (Cu)/reflection metal layer (alloy).

Then, for each of the substrates (Examples 4-1, 4-2 and ComparativeExamples 4-1 to 4-8), pull strength between metals forming each of thelayers was investigated. Further, it was verified whether coppercontained in the main body portion 11 diffused to the surface of thereflection metal layer 12C or not when each of the substrate was heated.The results are shown in Table 3.

TABLE 3 Pull strength be- Copper diffu- tween metals form- sion tosurface Overall Layer configuration ing each of layers during heatingevaluation Example 4-1 Main body ◯ (Good) ◯ (Good) ⊚ (Excellent) portion(copper substrate)/copper layer (Cu)/nickel layer (Ni)/gold layer(Au)/reflection metal layer (alloy) Example 4-2 Main body Δ (Fair)between ◯ (Good) ◯ (Good) portion (copper main body substrate)/nickelportion (copper layer (Ni)/gold substrate)/nickel layer (Au)//reflectionlayer (Ni) metal layer (alloy) ◯ (Good) between nickel layer (Ni)/goldlayer (Au)/reflection metal layer (alloy) Comparative Main body X (Poor)X (Poor) X (Poor) Example 4-1 portion (copper substrate)/reflectionmetal layer (alloy) Comparative Main body ◯ (Good) X (Poor) X (Poor)Example 4-2 portion (copper substrate)/copper layer (Cu)/reflectionmetal layer (alloy) Comparative Main body Δ (Fair) between ◯ (Good) ◯(Good) Example 4-3 portion (copper main body silver substrate)/silverportion (copper layer (Ag) layer (Ag)/reflection substrate)/silverexceeding metal layer (alloy) layer (Ag) 1 μm ◯ (Good) between X (Poor)silver layer Silver (Ag)/reflection layer (Ag) metal layer below 1 μm(alloy) Comparative Main body ◯ (Good) ◯ (Good) ◯ (Good) Example 4-4portion (copper silver substrate)/copper layer (Ag) layer (Cu)/silverexceeding layer (Ag)/reflection 1 μm metal layer (alloy) X (poor) Silverlayer (Ag) below 1 μm Comparative Main body Δ (Fair) between ◯ (Good) X(Poor) Example 4-5 portion (copper main body substrate)/nickel portion(copper layer (Ni)/reflection substrate)/nickel metal layer (alloy)layer (Ni) X (Poor) between nickel layer (Ni)/reflection metal layer(alloy) Comparative Main body ◯ (Good) between ◯ (Good) X (Poor) Example4-6 portion (copper main body substrate)/copper portion (copper layer(Cu)/nickel substrate)/copper layer (Ni)/reflection layer (Cu)/nickelmetal layer (alloy) layer (Ni) X (Poor) between nickel layer (Ni)/reflection metal layer (alloy) Comparative Main body Δ (Fair) between Δ(Fair) X (Poor) Example 4-7 portion (copper main body (remarkablesubstrate)/nickel portion (copper when layer (Ni)/coppersubstrate)/nickel reflection layer (Cu)/reflection layer (Ni) metallayer metal layer (alloy) ◯ (Good) between (alloy) is nickel layer below1 μm) (Ni)/copper layer (Cu)/reflection metal layer (alloy) ComparativeMain body ◯ (Good) between Δ (Fair) X (Poor) Example 4-8 portion (coppermain body (remarkable substrate)/copper portion (copper when layer(Cu)/nickel substrate)/copper reflection layer (Ni)/copper layer(Cu)/nickel metal layer layer (Cu)/reflection layer (Ni) (alloy) ismetal layer (alloy) ◯ (Good) between below 1 μm) nickel layer(Ni)/copper layer (Cu)/ reflection metal layer (alloy) ◯: goodbondability ◯: No diffusion

As shown in Table 3, in the substrates 10C according to Examples 4-1 and4-2, pull strength between metals forming each of layers wassatisfactory and copper was not diffused to the surface of thereflection metal layer 12C during heating.

In the substrates according to Comparative Examples 4-3 and 4-4, thepull strength between metals forming each of the layers was satisfactoryand, when the thickness of the silver layer (Ag) exceeds 1 μm, copperwas not diffused to the surface of the reflection metal layer 12C duringheating. However, when the thickness of the silver layer (Ag) was below1 μm, a phenomenon of copper diffusion to the surface of the reflectionmetal layer 12C was observed during heating.

In the substrates according to other comparative examples (ComparativeExamples 4-1, 4-2, and 4-5 to 4-8), the pull strength between metalsforming each of the layers was partially lower (Comparative Examples4-3, 4-5, 4-6, and 4-7), or copper diffusion occurred at the surface ofthe reflection metal layer 12C during heating (Comparative Examples 4-3,4-4, 4-7, and 4-8).

In each of the substrates (Examples 4-1, 4-2, and Comparative Examples4-1 to 4-8), while the alloy of gold (Au) and silver (Ag) is used forthe reflection metal layer, identical results can be obtained even whenthe alloy of platinum (Pt) and silver (Ag) is used.

Two types of substrates (Example 4-A, and Comparative Example 4-A) shownbelow were manufactured.

Example 4-A

A substrate 10C (Example 4-A) was manufactured by stacking the copperlayer 16 (0.1 μm thickness), the nickel layer 17 (1 μm thickness), andthe gold layer 18 (0.01 μm thickness) successively over the main bodyportion 11 comprising a copper substrate, and forming the reflectionmetal layer 12C comprising the alloy of gold and silver on the goldlayer 18. In this case, the reflection metal layer 12C has a compositioncontaining 50% by weight of gold and the balance being silver and anevitable impurity.

Comparative Example 4-A

A substrate (Comparative Example 4-1) was manufactured by forming thecopper plating layer (0.1 μm thickness) on the main body portion 11comprising the copper plate, and forming a silver plating layer (3 μmthickness) on the copper plating layer. The substrate (ComparativeExample 4-A) was identical with the substrate according to ComparativeExample 1-A described above.

<Initial Reflectance>

The reflectance (initial reflectance) at the surface of the two types ofthe substrates (Example 4-A and Comparative Example 4-A) was measured.

<Reflectance after Heat Resistance Test>

Further, for evaluating the heat resistance of the two types of thesubstrates (Example 4-A and Comparative Example 4-A), heat resistancetest was carried out on each of the substrates. Specifically, each ofthe substrates was left in an atmosphere at 150° C. for 1008 hours (42days). Then, the reflectance (reflectance after the heat resistancetest) was measured by the same method as in the case of the initialreflectance.

The results are shown in FIG. 60. FIG. 60 is a graph showing the initialreflectance and the reflectance after the heat resistance test incomparison for Example 4-A and Comparative Example 4-A.

As a result, in the substrate of Example 4-A (nickel/gold/gold-silveralloy), it was found that the reflectance after the heat resistance wasnot changed greatly from the initial reflectance, the heat resistance ofthe reflection metal layer 12C was improved, and the reflectance wasless likely to be lowered by the heat.

In the substrate of Comparative Example 1-A (silver), the reflectanceafter the heat resistance test was remarkably lowered from the initialreflectance. Accordingly, it can be said that the reflectance of thesilver plating layer may possibly be lowered by the heat.

<Reflectance after Solution Test>

Then, for investigating the sulfurization resistance of the two types ofthe substrates (Example 4-A and Comparative Example 4-A), a solutiontest was carried out on each of the substrates and the reflectance afterthe solution test was measured.

<Reflectance after Gas Test>

Further, for investigating the sulfurization resistance of the two typesof the substrates (Example 4-A and Comparative Example 4-A), a gas testwas carried out on each of the substrates and the reflectance after thesolution test was measured.

<Continuity of Wire Bonding (W/B)>

It was investigated whether wire bonding could be applied continuouslyon the surface of the two types of the substrates (Example 4-A andComparative Example 4-A) described above.

<Strength of Wire Bonding (W/B)>

Wire pull strength was investigated when wire bonding was performed onthe surface of the two types of the substrates (Example 4-A andComparative Example 4-A) described above.

<Solder Wettability>

Solder wettability of the two types of the substrates (Example 4-A andComparative Example 4-A) was investigated.

Measuring methods for the initial reflectance, reflectance after thesolution test, the reflectance after the gas test, the continuity ofwire bonding (W/B), the wire bonding (W/B) strength, and the solderwettability are identical with those of the first embodiment describedabove (Example 1-A, Example 1-B, Comparative Example 1-A).

The results are collectively shown in Table 4.

TABLE 4 Evaluation for sulfurization resistance Initial (wavelength 460nm) Corrosion reflectance Reflectance Reflectance Solder resistantplating (wavelength 400 after solution after gas W/B evaluationwettability composition to 460 nm) test (U-5) test (1H) ContinuityStrength Zero cross Example 4-A 33 to 68% 59% 52% ⊚ (Excellent) 8.4 g1.2 sec (nickel/gold/gold silver alloy) Comparative 85 to 92% 22% 36% ⊚(Excellent) 7.0 g 0.9 sec Example 4-A (silver)

As a result, in the substrate of Example 4-A (nickel/gold/gold-silveralloy), it was found that both of the reflectance after the solutiontest and the reflectance after the gas test were scarcely changed fromthe initial reflectance, and that the reflection metal layer 12C wasless likely to be corroded by a corrosive gas such as a hydrogen sulfidegas.

In the substrate of Comparative Example 4-A (silver), both thereflectance after the solution test and the reflectance after the gastest were lowered remarkably from the initial reflectance and it can besaid that the silver plating layer may possibly be corroded by acorrosive gas such as a hydrogen sulfide gas.

Further, the two types of substrates (Example 4-A and ComparativeExample 4-A) exhibited good results in all of the continuity of the wirebonding (W/B), the wire bonding (W/B) strength, and the solderwettability.

The invention claimed is:
 1. An LED resin-attached leadframe comprising:a die pad for mounting an LED element; a lead portion disposed in aspaced relation to the die pad; and an outer resin portion formed on thedie pad and the lead portion, wherein the die pad and the lead portionhave an opposing surface, respectively, the opposing surface of the diepad and the opposing surface of the lead portion opposing each otherover a space between the die pad and the lead portion, and the opposingsurface of the die pad and the opposing surface of the lead portionbeing in asymmetry with respect to each other, the opposing surface ofthe die pad has a first middle protrusion positioned in a middle portionof the die pad in a thickness direction of the die pad and protrudingtoward the space, and an upper protrusion positioned in an upper surfaceside of the die pad and protruding toward the space, the opposingsurface of the lead portion has a second middle protrusion positioned ina middle portion of the lead portion in a thickness direction of thelead portion and protruding toward the space, the die pad has a mountingsurface for mounting the LED element and a bottom surface located on anopposite side of the mounting surface, in a vertical section of the diepad, a curved line is formed between the first middle protrusion of thedie pad and the bottom surface, the curved line curving toward themounting surface, the first middle protrusion of the die pad and thesecond middle protrusion of the lead portion are offset with respect toeach other in the thickness directions of the die pad and of the leadportion, the upper protrusion of the die pad is positioned closer to thelead portion than the first middle protrusion of the die pad, and theouter resin portion fills in the space between the die pad and the leadportion.
 2. A semiconductor device comprising: a die pad; a lead portiondisposed in a spaced relation to the die pad; an LED element mounted onthe die pad; an electroconductive portion for electrically connectingthe lead portion and the LED element; an encapsulating resin portion forencapsulating the LED element and the electroconductive portion; and anouter resin portion formed on the die pad and the lead portion andsurrounding a portion on which the LED element is mounted, wherein thedie pad and the lead portion have an opposing surface, respectively, theopposing surface of the die pad and the opposing surface of the leadportion opposing each other over a space between the die pad and thelead portion, and the opposing surface of the die pad and the opposingsurface of the lead portion being in asymmetry with respect to eachother, the opposing surface of the die pad has a first middle protrusionpositioned in a middle portion of the die pad in a thickness directionof the die pad and protruding toward the space, and an upper protrusionpositioned in an upper surface side of the die pad and protruding towardthe space, the opposing surface of the lead portion has a second middleprotrusion positioned in a middle portion of the lead portion in athickness direction of the lead portion and protruding toward the space,the die pad has a mounting surface for mounting the LED element and abottom surface located on an opposite side of the mounting surface, in avertical section of the die pad, a curved line is formed between thefirst middle protrusion of the die pad and the bottom surface, thecurved line curving toward the mounting surface, the first middleprotrusion of the die pad and the second middle protrusion of the leadportion are offset with respect to each other in the thicknessdirections of the die pad and of the lead portion, the upper protrusionof the die pad is positioned closer to the lead portion than the middleprotrusion of the die pad, and the outer resin portion fills in thespace between the die pad and the lead portion.
 3. A method formanufacturing an LED resin-attached leadframe comprising: a step ofetching a metal substrate so as to make a die pad for mounting an LEDelement and a lead portion disposed in a spaced relation to the die pad;and a step of forming an outer resin portion on the die pad and the leadportion, wherein the die pad and the lead portion have an opposingsurface, respectively, the opposing surface of the die pad and theopposing surface of the lead portion opposing each other over a spacebetween the die pad and the lead portion, and the opposing surface ofthe die pad and the opposing surface of the lead portion being inasymmetry with respect to each other, the opposing surface of the diepad has a first middle protrusion positioned in a middle portion of thedie pad in a thickness direction of the die pad and protruding towardthe space, and an upper protrusion positioned in an upper surface sideof the die pad and protruding toward the space, the opposing surface ofthe lead portion has a second middle protrusion positioned in a middleportion of the lead portion in a thickness direction of the lead portionand protruding toward the space, the die pad has a mounting surface formounting the LED element and a bottom surface located on an oppositeside of the mounting surface, in a vertical section of the die pad, acurved line is formed between the first middle protrusion of the die padand the bottom surface, the curved line curving toward the mountingsurface, the first middle protrusion of the die pad and the secondmiddle protrusion of the lead portion are offset with respect to eachother in the thickness directions of the die pad and of the leadportion, the upper protrusion of the die pad is positioned closer to thelead portion than the first middle protrusion of the die pad, and theouter resin portion fills in the space between the die pad and the leadportion.
 4. A method for manufacturing a semiconductor devicecomprising: a step of etching a metal substrate so as to make a die padfor mounting an LED element and a lead portion disposed in a spacedrelation to the die pad; a step of forming an outer resin portion on thedie pad and the lead portion; a step of mounting the LED element overthe die pad; a step of connecting the LED element and the lead portionby an electroconductive portion; and a step of encapsulating the LEDelement and the electroconductive portion by a light permeableencapsulating resin portion, wherein the die pad and the lead portionhave an opposing surface, respectively, the opposing surface of the diepad and the opposing surface of the lead portion opposing each otherover a space between the die pad and the lead portion, and the opposingsurface of the die pad and the opposing surface of the lead portionbeing in asymmetry with respect to each other, the opposing surface ofthe die pad has a first middle protrusion positioned in a middle portionof the die pad in a thickness direction of the die pad and protrudingtoward the space, and an upper protrusion positioned in an upper surfaceside of the die pad and protruding toward the space, the opposingsurface of the lead portion has a second middle protrusion positioned ina middle portion of the lead portion in a thickness direction of thelead portion and protruding toward the space, the die pad has a mountingsurface for mounting the LED element and a bottom surface located on anopposite side of the mounting surface, in a vertical section of the diepad, a curved line is formed between the first middle protrusion of thedie pad and the bottom surface, the curved line curving toward themounting surface, the first middle protrusion of the die pad and thesecond middle protrusion of the lead portion are offset with respect toeach other in the thickness directions of the die pad and of the leadportion, the upper protrusion of the die pad is positioned closer to thelead portion than the first middle protrusion of the die pad, and theouter resin portion fills in the space between the die pad and the leadportion.
 5. The LED resin-attached leadframe according to claim 1,wherein a mount portion which is to be mounted on the LED element isformed on a thin section of the die pad.
 6. The semiconductor deviceaccording to claim 2, wherein a mount portion which mounts on the LEDelement is formed on a thin section of the die pad.
 7. The method formanufacturing an LED resin-attached leadframe according to claim 3,wherein a mount portion which is to be mounted on the LED element isformed on a thin section of the die pad.
 8. The method for manufacturinga semiconductor device according to claim 4, wherein a mount portionwhich mounts on the LED element is formed on a thin section of the diepad.